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josmiceli answered: 9695 problems
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Geometry_Word_Problems/428550: You are 90 ft from a tree. The angle of elevation from your eyes, which are 5 ft off the ground, to the top of the tree is 70 degrees. to the nearest foot, how tall is the tree?
1 solutions

Answer 297853 by josmiceli(9697) About Me  on 2011-03-29 08:33:50 (Show Source):
You can put this solution on YOUR website!
Call the height of the tree +h+
You have a right triangle
The base is 90 ft
The height is +h+-+5+
+tan%2870%29+=+%28h-5%29%2F90+
+2.747+=+%28h-5%29%2F90+
+h+-+5+=+90%2A2.747+
+h+=+5+%2B+247.27+
+h+=+252.3+
The tree is 252 ft high


Mixture_Word_Problems/428346: Assume you have sea water that weighs 64lb/ft3 and contains 35 parts per thousand (0.0035) dissolved salt by weight. How many cubic feet of the sea water would you need to place in an evaporation basin to collect 125lb of sea salt.
1 solutions

Answer 297767 by josmiceli(9697) About Me  on 2011-03-28 19:55:03 (Show Source):
You can put this solution on YOUR website!
+64+ lbs/ft3 x x ft3 x +.0035+ = 125+ lb
x+=+125+%2F+%2864%2A.0035%29+
x+=+558.036+ ft3


Miscellaneous_Word_Problems/428216: A hot air balloon is seen over Seven Springs simultaneously by two observers standing at two different points on the ground. ( The 2 people are facing each other and the balloon is in between them in the air.) They are 1.75 miles apart on ground level. The angles of elevation are 33 degrees and 37 degrees respectively. How high above the ground is the balloon?
1 solutions

Answer 297713 by josmiceli(9697) About Me  on 2011-03-28 17:03:10 (Show Source):
You can put this solution on YOUR website!
Locate the point which is directly below the balloon. Call the point (C)
The person who sees the balloon at 37 degrees elevation
is looking higher, so that person is closer to the balloon.
Call their position (A)
Call the position of the other person (B)
Call the position of the balloon (D)
given:
AB = 1.75 miles
------------
+tan%2837%29 = DC / AC
and, for the other person,
+tan%2833%29 = DC / BC
------------
.7536 = DC / AC
.6494 = DC / BC
-------------
DC = .7536 x AC
DC = .6494 x BC
-------------
.7536 x AC = .6494 x BC
and
Since AB = AC + BC
1.75 = AC + BC
AC = 1.75 - BC
--------------
.7536 x (1.75 - BC) = .6494 x BC
Solve this for BC, then plug answer
back into .6494 = DC / BC
to get the height, DC





Numbers_Word_Problems/428235: Salisbury High School decided to take their students on a field trip to a theme park. A total of 150 people went on the trip. Adults pay $45.00 for a ticket and students pay $28.50 for a ticket. How many students and how many adults went to the park if they paid a total of $4770?
1 solutions

Answer 297705 by josmiceli(9697) About Me  on 2011-03-28 16:40:59 (Show Source):
You can put this solution on YOUR website!
+s+= number of students on trip
+a+ = number of adults on trip
given:
(1) +s+%2B+a+=+150+
(2) 4500a+%2B+2850s+=+477000+ (in cents)
----------------
Multiply both sides of (1) by 2850
and subtract (1) from (2)
(2) 4500a+%2B+2850s+=+477000+
(1) -2850a+-+2850s+=+-427500+
+1650a+=+49500+
+a+=+30+
and, since
(1) +s+%2B+a+=+150+
(1) +s+%2B+30+=+150+
+s+=+120+
There were 30 adults and 120 students
check:
(2) 4500a+%2B+2850s+=+477000+
(2) 4500%2A30+%2B+2850%2A120+=+477000+
+135000+%2B+342000+=+477000+
+477000+=+477000+
OK


Systems-of-equations/428228: My instructions are simply to "solve" the equation is 3x-(5-4x)=2(4x+2)+1

I've tried doing it and I stopped once I got -5=x+6 it didn't seem right, so I didn't finish it.
1 solutions

Answer 297701 by josmiceli(9697) About Me  on 2011-03-28 16:29:01 (Show Source):
You can put this solution on YOUR website!
+3x-%285-4x%29=2%284x%2B2%29%2B1+
+3x+-+5+%2B+4x+=+8x+%2B+4+%2B+1+
+7x+-+5+=+8x+%2B+5+
Now subtract 7x from both sides
+-5+=+x+%2B+5+
Subtract 5 from both sides. This is the same
as adding a -5 to both sides
+-10+=+x+ answer
You can do a check by plugging this back
into original equation:
+3x-%285-4x%29=2%284x%2B2%29%2B1+
+3%2A%28-10%29+-+%285-4%2A%28-10%29%29=2%284%2A%28-10%29%2B2%29%2B1+
Now work from the inside of the parentheses outward
+-30+-+%285+-+4%2A%28-10%29%29=2%28-40%2B2%29%2B1+
+-30+-+%285+%2B+40%29+=+2%2A%28-38%29+%2B1+
+-30+-+45+=+-76+%2B+1+
+-75+=+-75+
OK


Linear-equations/428225: The slope of the line that contains the points (4, 10) and (5, 13) is 3. Find the y-intercept
1 solutions

Answer 297699 by josmiceli(9697) About Me  on 2011-03-28 16:15:31 (Show Source):
You can put this solution on YOUR website!
You can express the equation as
+y+=+mx+%2B+b+
+y+=+3x+%2B+b+ (b is the y-intercept)
Just plug in one of the points
(4,10)
10+=+3%2A4+%2B+b+
+b+=+10+-+12+
+b+=+-2+ (answer)
Here's a plot:
+graph%28+400%2C+400%2C+-5%2C+5%2C+-5%2C+5%2C+3x+-+2%29+


logarithm/428215: How do you express 4^-3=1/64 in logarithmic form? When I did this question I got log base 4 of 64 equals -3. I just wanted to be sure I was doing it right.
1 solutions

Answer 297697 by josmiceli(9697) About Me  on 2011-03-28 16:09:11 (Show Source):
You can put this solution on YOUR website!
You're off a little
You can take the log to base 4 of both sides
+log%284%2C+4%5E%28-3%29%29+=+log%284%2C+1%2F64%29+
+-3+=+log%284%2C+1%2F64+%29


Miscellaneous_Word_Problems/428211: Jack usually mows his lawn in 8 hours. marilyn can mow the same yard in 6 hours. How much time would it take for them to mow the lawn together?
1 solutions

Answer 297694 by josmiceli(9697) About Me  on 2011-03-28 15:54:14 (Show Source):
You can put this solution on YOUR website!
You have to add their rates of mowing
In words:
( 1 lawn) / (Jack's time to mow it) + (1 lawn ) / (Marilyn's time to mow it) =
{1 lawn) / (Their time mowing it together)
----------------
given:
Jack's rate = 1%2F8 lawns/hour
Marilyn's rate = 1%2F6 lawns/hour
----------------
+1%2F8+%2B+1%2F6+=+1%2Ft+
Multiply both sides by 24t
+3t+%2B+4t+=+24+
+7t+=+24+
+t+=+3.43+ hrs
or, about 3 hours and 26 minutes


Problems-with-consecutive-odd-even-integers/428205: Name the set of 4 consecutive odd integers starting with -3.
1 solutions

Answer 297691 by josmiceli(9697) About Me  on 2011-03-28 15:43:08 (Show Source):
You can put this solution on YOUR website!
You must count every other integer starting
with an odd integers in order to get only odd integers
If I call -3+=+n, then
n+=+-3
n+%2B+2+=+-1
n+%2B+4+=+1
n+%2B+6+=+3
The set is {-3,-1,1,3}


Equations/427920: Hii.. I'm really stuck on solving this:: 5x+3+(-x)=2x+1+2x+3 can u help me thanks
1 solutions

Answer 297517 by josmiceli(9697) About Me  on 2011-03-27 20:42:29 (Show Source):
You can put this solution on YOUR website!
+5x%2B3%2B%28-x%29=2x%2B1%2B2x%2B3+
Note that 2x+%2B+2x+=+4x, so the right side is
+5x%2B3%2B%28-x%29=4x%2B1%2B3+
Note that plus(minus) and minus(plus) = minus, so
+5x+%2B+3+-+x+=+4x+%2B+1+%2B+3+
Now subtract 3 from both sides
+5x+%2B+3+-+3+-+x+=+4x+%2B+1+%2B+3+-+3+
+5x+-+x+=+4x+%2B+1+
+4x+=+4x+%2B+1+
Subtract 4x from both sides
+0+=+1+
This is not true, so the original equation can't be true
If 1 is subtracted from the right side, then
The equation would be true for any x


Geometry_Word_Problems/427911: i dont know how to find my x and my y in this problem.
you want to fence a rectangular area of your yard for a garden. you plan to use no more than 50ft of fencing.
a. write a linear equation that describes the situation
1 solutions

Answer 297516 by josmiceli(9697) About Me  on 2011-03-27 20:31:23 (Show Source):
You can put this solution on YOUR website!
If the dimensions of the yard are x by y,
the perimeter is the distance around the yard.
+P+=+x+%2B+x+%2B+y+%2B+y+
+P+=+2x+%2B+2y+
given:
+2x+%2B+2y+%3C=+50+ ft
Divide both sides by 2
+x+%2B+y+%3C=+25+


Quadratic_Equations/427855: Find the area and perimeter of an 4 1/2-by-21-inch piece of paper.
Area ? square inches
Perimeter ? inches
Please write down the steps to get the answer. Thanks
1 solutions

Answer 297487 by josmiceli(9697) About Me  on 2011-03-27 18:53:01 (Show Source):
You can put this solution on YOUR website!
The paper is a rectangle
To find area, multiply the sides
+A+=+4.5+%2A+21+
+A+=+94.5+ in2
To find the perimeter, add up the 4 sides
P+=+4.5+%2B+4.5+%2B+21+%2B+21+ in
P+=+51 in
Note that area is in square inches, and
perimeter is in inches


Linear-equations/427332: During one year, the Peddys' real estate bill included $948 for county improvements. Of this amount, $308 went for transportation and roads. What percent did the Peddy family pay for transportation and roads?
Round your answer to two decimal places
1 solutions

Answer 297186 by josmiceli(9697) About Me  on 2011-03-26 11:38:17 (Show Source):
You can put this solution on YOUR website!
Per cent means "per one hundred"
+x%2F100+=+308%2F948
Multiply both sides by 100%2A948
948x+=+30800
+x+=+30800%2F948
+x+=+32.489+
The family paid 32.49% for transportation and roads.


Polynomials-and-rational-expressions/427325: how would you find the greatest common factor of 8ab^3 and 2ab^2?
please explain.
1 solutions

Answer 297183 by josmiceli(9697) About Me  on 2011-03-26 11:33:03 (Show Source):
You can put this solution on YOUR website!
It is the same problem as
"What is the greatest common factor of
30 and 48?"
3 divides both of them, but so does 6,
so that's the answer.
Looking at +8a%2Ab%5E3 and 2a%2Ab%5E2,
I see that 2 is a common factor, so is
a and b%5E2. Note that b%5E3 will
not divide into 2a%2Ab%5E2 evenly.
-----------------
2a%2Ab2 is the common factor because
2a%2Ab%5E2+%2F+%282a%2Ab%5E2%29+=+1
and
8a%2Ab%5E3+%2F+%282a%2Ab%5E2%29+=+4b
Note that there is no remainder in the divisions.


Exponents-negative-and-fractional/427202: I need to graph these two linear equations x+y=9 and x-y=3
1 solutions

Answer 297083 by josmiceli(9697) About Me  on 2011-03-25 20:49:29 (Show Source):
You can put this solution on YOUR website!
+x+%2B+y+=+9+
+y+=+-x+%2B+9+
and
+x+-+y+=+3+
+y+=+x+-+3+
Here's the plot:
+graph%28+400%2C+400%2C+-10%2C+10%2C+-10%2C+10%2C+-x+%2B+9%2C+x+-+3%29+


Quadratic_Equations/427200: I am trying to find a way to solve this problem.
A gravel path of equal width is to be built around a 8' by 8' square garden. How wide can the path be if there is enough gravel for 80 square ft?
1 solutions

Answer 297082 by josmiceli(9697) About Me  on 2011-03-25 20:45:14 (Show Source):
You can put this solution on YOUR website!
You are putting 80 square feet around +8%2A8+=+64+ square feet
Adding these, 80+%2B+64+=+144 square feet. These combined areas
have to be a square, since the path surrounds a square.
+sqrt%28144%29+=+12+ ft is a side of the square.
The path width is +%281%2F2%29%2A%2812+-+8%29+=+2
The path is 2 ft wide
check:
+%282+%2B+2+%2B+8%29%5E2+=+144+
OK


Quadratic_Equations/427167: what are the solutions to the equation x^2+7x=-12
1 solutions

Answer 297066 by josmiceli(9697) About Me  on 2011-03-25 19:23:17 (Show Source):
You can put this solution on YOUR website!
x%5E2%2B7x=-12
To complete the square, take 1/2 of the
coefficient of x, square it, and add
it to both sides
+x%5E2+%2B+7x+%2B+%287%2F2%29%5E2+=+-12+%2B+%287%2F2%29%5E2+
+x%5E2+%2B+7x+%2B+49%2F4+=+-48%2F4+%2B+49%2F4+
+%28+x+%2B+7%2F2+%29%5E2+=+1%2F4+
take the square root of both side
+x+%2B+7%2F2+=+1%2F2+
+x+=+-3+
and
+x+%2B+7%2F2+=+-1%2F2+
+x+=+-4+
----------
You can check by plugging in -3 for x
and then -4 for x


percentage/427175: Cece scored a 78 on her first math test. She scored an 84 on her second test. What is the percent increase, rounded to the nearest tenth, from Cece’s first score to her second score?
1 solutions

Answer 297065 by josmiceli(9697) About Me  on 2011-03-25 19:06:25 (Show Source):
You can put this solution on YOUR website!
The increase is 84+-+78+=+6
Let x = percent gain
+x%2F100+=+6%2F78+
+78x+=+600+
+x+=+7.692+
7.7 percent increase


Money_Word_Problems/427050: Company A sold 14.7 million dollars of electronics equipment in 2000 and its sales have increased by 2.1 million dollars each year. Company B sold 19.4 million dollars of electric equipment in 2000 and its sales have increased by 1.7 million each year.
1) Let A (t) and B (t) repesent the sales (in millions of dollars) by company A and compnay B, respectively, at t years since 2000. Find equations for A and B.
2) Predict when sales at the companies will be equal. What will that sales be?
1 solutions

Answer 297004 by josmiceli(9697) About Me  on 2011-03-25 13:03:54 (Show Source):
You can put this solution on YOUR website!
Let S = sales for the year
Let t = the year
Plot Sales on the vertical axis and the year on the horizontal
You are given a point (2000,14.7) for company A.
I'll call it (0,14.7)
The rate of increase, or slope is +2.1+ millions/year
To get the equation:
+%28+S+-+14.7%29+%2F+%28+t+-+0+%29+=+2.1+ (in millions)
+S+-+14.7+=+2.1t+
+S+=+2.1t+%2B+14.7+
-------------------------
For company B, the point is (0,19.4),
and the slope is +1.7+ millions/year
+%28S+-+19.4%29+%2F+%28t+-+0%29+=+1.7+
+S+-+19.4+=+1.7t+
+S+=+1.7t+%2B+19.4+
------------------------
To find where the lines intersect (equal amount of sales),
Subtract B's equation from A's
+S+=+2.1t+%2B+14.7+
+-S+=+-1.7t+-+19.4+
+0+=+.4t+-+4.7+
+.4t+=+4.7+
+t=+11.75+
If the data is year-end data, then this figure means
9 months into 2012, or September 2012
Hope I got it right




test/426991: Evaluate (-x)2 and-x2 when x=3
1 solutions

Answer 296966 by josmiceli(9697) About Me  on 2011-03-25 08:27:16 (Show Source):
You can put this solution on YOUR website!
+%28-3%29%5E2+=+%28-3%29%2A-3+
%28-3%29+%2A-3+=+9+
-------------
+-3%5E2+=+-%283%2A3%29+
+-%283%2A3%29+=+-9+


Age_Word_Problems/426990: When Tim started football 3 years ago, his coach was twice his age. Currently, Tim's coach is 10 years older than him. How old is Tim now?
1 solutions

Answer 296965 by josmiceli(9697) About Me  on 2011-03-25 08:24:01 (Show Source):
You can put this solution on YOUR website!
Let t = Tim's age now
Let c = Coach's age now
-----------------------
given:
(1) +c+-+3+=+2%2A%28t+-+3%29+
(2) +c+=+t+%2B+10+
----------------
Substitute (2) into (1)
(1) +t+%2B+10+-+3+=+2%2A%28t+-+3%29+
(1) +t+%2B+7+=+2t+-+6+
(1) +t+=+13+
Tim is 13 now
check:
(1) +c+-+3+=+2%2A%28t+-+3%29+
+c+-+3+=+2%2A%2813+-+3%29+
+c+=+20+%2B+3+
+c+=+23+
This is 10 years older than Tim is now


Linear_Equations_And_Systems_Word_Problems/426987: A box has a volume of 100 cubic cm and the area of the bottom of the box is 50 square cm. Find the height of the box?
1 solutions

Answer 296962 by josmiceli(9697) About Me  on 2011-03-25 08:13:35 (Show Source):
You can put this solution on YOUR website!
Given:
V+=+100 cm3
+b+=+50+ cm2
--------------
+V+=+b%2Ah+ cm3
+100+=+50%2Ah+ cm3
+h+=+2+ cm


Travel_Word_Problems/426915: Nestor finished a 42-kilometer race in 1 hour and 45 minutes. What was his average speed in kilometers per hour?
Please explain how to get the answer.
Thanks, Sparrow
1 solutions

Answer 296879 by josmiceli(9697) About Me  on 2011-03-24 21:41:40 (Show Source):
You can put this solution on YOUR website!
You need an answer in km/hr, so you must covert 1 hour and 45 minutes to hours
To convert minutes to hours, the units are:
(minutes) x (hours/minute) = hours
Plugging in numbers:
+45%2A%281%2F60%29+=+3%2F4+, so there are 3%2F4 hours in 45 minutes
Speed is (distance) / (time)
+42+%2F+%281+%2B+3%2F4%29 km/hr
+42+%2F+1.75 km/hr
+24+ km/hr


Percentage-and-ratio-word-problems/426908: The ratio of apples in Barbara's store to those in Mark's store was 8:1. Barbara gave half her apples to Mark, and then Mark had 6 more apples than Barbara. How many apples did Barbara have first?
1 solutions

Answer 296874 by josmiceli(9697) About Me  on 2011-03-24 21:33:22 (Show Source):
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Let x = number of apples Mark started with
8x = Number Barbara started with
given:
+x+%2B+8x%2F2+=+8x%2F2+%2B+6
+x=+6+
+8x+=+48+
Barbara started with 48 apples
check:
Barbara gives 24 to Mark
Now Mark has 30
This is 6 more than Barbara's
OK


Coordinate-system/426862: What is the slope of a line that contains the coordinate points (7,-3) and (-2,5)?
1 solutions

Answer 296848 by josmiceli(9697) About Me  on 2011-03-24 20:22:41 (Show Source):
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The slope is (change in y) / (change in x), so
given:
(7,-3) and (-2,5)
slope = +%28+5+-%28-3%29%29+%2F+%28-2+-+7%29+=+8%2F%28-9%29+
slope = +-8%2F9+


Money_Word_Problems/426856: Juan goes to a bank and gets change for a
$50 bill consisting of all $5 bills and $1 bills. There are
22 bills in all. How many of each kind are there?
1 solutions

Answer 296846 by josmiceli(9697) About Me  on 2011-03-24 20:19:03 (Show Source):
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Let a = number of $5 bills
Let b = number of $1 bills
given:
(1) +a+%2B+b+=+22+
(2) +5a+%2B+b+=+50+
----------------
(1) b+=+22+-+a+
By substitution:
(2) +5a+%2B+22+-+a+=+50+
+4a+=+28+
+a+=+7+
and
(1) +a+%2B+b+=+22+
+b+=+22+-+7+
+b+=+15+
There are 7 $5 bills and 15 $1 bills


Polynomials-and-rational-expressions/426739: The initial velocity of a rocket shot straight upward is 40 ft/sec. The height of the rocket after t seconds is given by the formula h(t) = -16t(squared) + 40 t. What is the maximum height the rocket reaches? When will it land? Show and explain work.
1 solutions

Answer 296822 by josmiceli(9697) About Me  on 2011-03-24 18:27:49 (Show Source):
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+h%28t%29+=+-16t%5E2+%2B+40t+
The maximum height occurs at
+t%5Bmax%5D+=+-b%2F%282a%29+ where
a+=+-16
b+=+40
+-b%2F%282a%29+=+-40%2F%282%2A-16%29+
+t%5Bmax%5D+=+5%2F4+
To find the max height,
+h%285%2F4%29+=+-16%2A%285%2F4%29%5E2+%2B+40%2A%285%2F4%29+
+h%285%2F4%29+=+-+25+%2B+50+
The max height is 25 ft
It will land when h+=+0
+0+=+-16t%5E2+%2B+40t+
+0+=+8t%2A%28-2t+%2B+5%29+
There are 2 ways for h(t) to be zero,
+8t+=+0+
+t+=+0+ ( at takeoff), and
+-2t+%2B+5+=+0
2t+=+5
+t+=+5%2F2+
The rocket will land in 2.5 sec
check answer:
+h%28t%29+=+-16t%5E2+%2B+40t+
+0+=+-16%2A2.5%5E2+%2B+40%2A2.5+
+0+=+-16%2A6.25+%2B+100+
+0+=+-100+%2B+100+
+0=+0+
OK
Here's a plot:
+graph%28+400%2C+400%2C+-1%2C+3%2C+-1%2C+30%2C+-16x%5E2+%2B+40x%29+


Unit_Conversion_Word_Problems/426490: A car traveled 281 miles in 4 hours 41 minutes. What was the average speed of the car in miles per hour?
Please show me how did you get the answer. Thank you.
1 solutions

Answer 296673 by josmiceli(9697) About Me  on 2011-03-24 03:11:53 (Show Source):
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You just need to express 4 hrs 41 min in terms of hours. Then
you will have an answer in miles/hour
The simplest expression, since 41 has no divisors is
+4+ hours + 41%2F60 (min/(min/hr) =
+240%2F60+%2B+41%2F60+=+281%2F60+ hrs
+281+%2F+%28281%2F60%29+=+60+
The average speed is 60 mi/hr
Note that 240%2F60 is not a conversion, it
is just another way to express 4 hrs


logarithm/426485: How to simplify log2(0.5)^4?. I tryed it and my answer wasn't right. My answer was 1, -4, -0.90 and 2
1 solutions

Answer 296671 by josmiceli(9697) About Me  on 2011-03-24 02:56:34 (Show Source):
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It's a little confusing the way you present it
Is it:
log%282%2C.5%5E4%29
or is it
%28log%282%2C.5%29%29%5E4
I'm guessing it's the first one
The general rule is:
+log%28a%5Eb%29+=+b%2Alog%28a%29+, so
+log%282%2C.5%5E4%29+=+4%2A%28log%282%2C.5%29%29
note that
log%282%2C.5%29+=+log%282%2C2%5E%28-1%29%29
From the above rule, this is
+%28-1%29%2Alog%282%2C2%29+ so, the whole thing is:
+4%2A%28-1%29%2Alog%282%2C2%29+=+-4 answer


test/426456: Hi i really need help with my homework. I dont know how to do this problem.
"Through point (3,1) with the same slope as line 2x-3y=1"
1 solutions

Answer 296645 by josmiceli(9697) About Me  on 2011-03-23 23:45:43 (Show Source):
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First, get the equation into the form
+y+=+m%2Ax+%2B+b+
In this form, m = slope
given:
+2x+-+3y+=+1+
Subtract 2x from both side
+-3y+=+-2x+%2B+1+
Divide both sides by -3
+y+=+%282%2F3%29%2Ax+-+1%2F3+
+m+=+2%2F3+
Any line parallel to this one will also have +m+=+2%2F3+
So far you have
+y+=+%282%2F3%29%2Ax+%2B+b+ for the new line
It goes through (3,1), so I can plug this x and y into equation
to get b
+1+=+%282%2F3%29%2A3+%2B+b+
+1+=+2+%2B+b+
+b+=+-1+
So, the equation is
y+=+%282%2F3%29%2Ax+-+1 answer
Check: Does it go through (3,1)?
+1+=+%282%2F3%29%2A3+-+1+
+1+=+2+-+1+
+1+=+1+
OK


Equations/426458: what is the first step in solving the equation x + 78 = 135
1 solutions

Answer 296642 by josmiceli(9697) About Me  on 2011-03-23 23:33:35 (Show Source):
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+x+%2B+78+=+135+
You always want to get the unknown by itself, so
subtract 78 from both sides.
( anything you do to one side, you must do to the other)
+x+%2B+78+-+78+=+135+-+78+
+x+=+57+ answer