Questions on Algebra: Systems of Linear Equations answered by real tutors!

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Question 892804: A certain concrete mixture contains 5% cement and 8% sand. How many pounds of this mixture and how many pounds of sand should be combined with 255 pounds of cement to make a batch that is 12% cement and 15% sand? Set-up is my issue
Click here to see answer by josmiceli(19441)

Question 892924: Solve the system of equations by substitution. What is the solution for x?
2x + y = 1
4x + 2y = -1
Click here to see answer by Fombitz(32388)

Question 893076: In a first race, A gives b a Headstart of 100 feet and overtakes him in four minutes. In the second race he gains 750 feet on B when B runs 9000 feet. Find the rate at which each runs.
Click here to see answer by josmiceli(19441)

Question 893075: The farmer bought 100 acres of land, part at $370 and part at $450 an acre, paying for the whole $42,200. How much land was there in each part?
Click here to see answer by richwmiller(17219)

Question 893072: A potting mixture contains 12% peat Moss and 6% vermiculite. How much peat and how much vermiculite must be added to 100 pounds of this mixture to produce a new mixture having 15% Peat and 15% vermiculite?
Click here to see answer by josgarithmetic(39617)

Question 893074: A Carpenter and a helper can do a certain job in 15 days. If the Carpenter works 1.5 times as fast as the helper, how long would it take each to do the job, working alone?
Click here to see answer by josgarithmetic(39617)

Question 893073: If the width of a certain rectangle is increased by three and the length is reduced by four, we get a square with the same area as the original rectangle. Find the length and width of the original rectangle.
Click here to see answer by ankor@dixie-net.com(22740)

Question 893334: 4x-3y=28
9x-y=-6

Click here to see answer by Fombitz(32388)

Question 893564: solve 3x - 4y = 6 and Ax = 12y = 20 are parallel - solve for A
Click here to see answer by Fombitz(32388)

Question 893681: 2x+y+z=9
-x-y+z=1
3x-y+z=9
I keep getting x=2 z=5 and y=0 but the solutions don't equal at the end.
Click here to see answer by Fombitz(32388)

Question 893754: Write in slope-intercept form the equation of the line that passes through (-2,5) and (4,6)
Click here to see answer by richwmiller(17219)

Question 893754: Write in slope-intercept form the equation of the line that passes through (-2,5) and (4,6)
Click here to see answer by lwsshak3(11628)

Question 893939: The value of a gold coin picturing the head of the Roman Emperor Domitian is increasing at the rate of 7% per year. If the coin is worth $105 now, what will it be worth in 11 years?
Click here to see answer by Alan3354(69443)

Question 893940: A radioactive isotope has a half-life of 14 hours. Find the amount of the isotope left from a 320-milligram sample after 42 hours. If necessary, round your answer to the nearest thousandth.

Click here to see answer by Alan3354(69443)

Question 893964: How can I solve 50x + 100y = 0? If you could do an example problem like this, that would be fantastic! Thank you so much.
Click here to see answer by josgarithmetic(39617)

Question 894033: Find the sum or difference. Write the answer in standard form.
i^√2 + 7 - (9 + 7i^√2) - (7 - i^√2)
Click here to see answer by Fombitz(32388)

Question 894345: Which of the following points is a solution to the system of equations shown?
4x + y = 1
y = x + 6
Click here to see answer by Fombitz(32388)

Question 894352: 1. y=-3x-6;A(2,0)
2. -x-4y=-14;A(-6,2)
3. x+6y=40;A(-10,5)
4. 2x-y=7;A(3,-1)

Click here to see answer by Fombitz(32388)

Question 894361: Determine if the solution set for the system of equations shown is the empty set, contains one point or is infinite.
x - y = 5
2x + y = 1

Click here to see answer by richwmiller(17219)

Question 894639: sum of two numbers is 76 and difference is 34.find those numbers.equation should be in one variable.
Click here to see answer by Alan3354(69443)

Question 894568: x+y=2 2y+5z=7 3x-2z=1?

Click here to see answer by Fombitz(32388)

Question 895039: My problem is 13-4r=5(r+8). My objective is to solve the equation. Help?
Click here to see answer by josgarithmetic(39617)

Question 895235: "Solve" the following linear system using substitution and interpret the results. (4 marks)
6xy−2x+4==3y+20

Click here to see answer by Alan3354(69443)

Question 895487: 2x+19=y y=x+7
Click here to see answer by Fombitz(32388)

Question 895585: What value of y forms the solution of the system defined by y = 11x + 1 and
11x + 12y = 12?

Click here to see answer by Edwin McCravy(20056)

Question 895585: What value of y forms the solution of the system defined by y = 11x + 1 and
11x + 12y = 12?

Click here to see answer by MathTherapy(10552)

Question 895774: what is 10x+3=11(x-1)?

Click here to see answer by Fombitz(32388)

Question 896247: let A=(6,-4) and B=(-2,-3) and C=(t, -8). find the value of t so that the point C lies on the same line as A and B
Click here to see answer by josgarithmetic(39617)

Question 896378: what would be the solution to 2x-y < 3
Click here to see answer by Alan3354(69443)

Question 896536: How do you factor 9k^2 - 25 ( The 2 in 9k^2 is to the 2nd power)
Click here to see answer by richwmiller(17219)

Question 896982: Find the ordered triple pair (x,y,z) for the following system:
[(3xy/x+y)]=5, [(2xz)/(x+z)=3)], [(yz)/(y+z)]=4
I tried multiplying to get rid of the fraction on the bottom but still end up with the combined variables. I think I need to do something with the reciprocals to break them apart, but I am totally stuck. Thanks.

Click here to see answer by richwmiller(17219)

Question 897096: give f(x)= (2x-6)/(5x-10)
find the domain

Thanks in advance!
Click here to see answer by josgarithmetic(39617)

Question 897099: given f(x)=(2x-6)/(5x-10)
find f(3) and f(-3)
I was thinking that it is 2(3)-6=0 and 2(-3)-6=0 and do same with 5x-10
but I don't know if that is correct way of solving it.
Thanks in advance.
Click here to see answer by josgarithmetic(39617)

Question 897255: Have my basic equations for the problem but don't know what to do next...Any help will be greatly appreciated.
A cashier has a total of 30 bills consisting of ones, fives and twenties. The number of twenties is 6 less than the number of ones. The total value of money is $214. How many of each denomination of bill are there?
The equations I came up with are:
z=x-6
x+y+z=30
x+5y+20z=214
Click here to see answer by josgarithmetic(39617)

Question 897281: Y=2x+10
2x+y=6
Click here to see answer by Fombitz(32388)

Question 897395: given 120x-2y=9000
If you can just show me how to start the problem to find x and y intercept. Don't need answer.

Thanks in advance
Click here to see answer by Fombitz(32388)

Question 897390: f(x)= (2x-6)/(5x-10)
1. find f(-3) and f(3)

Thanks in advance!
Click here to see answer by Fombitz(32388)

Question 897416: 120x-2y=9000
x int (75,0)
y int (0,-4500)
How do I use the formula y=mx+b to graph the function?

Thanks in advance!
Click here to see answer by Fombitz(32388)

Question 897745: solve by cramers rule:
x+y+z = 6
y+z+w =7
z+w+x = 8
w+ x + y = 9
Click here to see answer by richwmiller(17219)

Question 897745: solve by cramers rule:
x+y+z = 6
y+z+w =7
z+w+x = 8
w+ x + y = 9
Click here to see answer by Fombitz(32388)

Question 898067: Solve the equation (2x^2)*y+4y=2x for y as a function of x. Express your answer in calculator syntax form.
Click here to see answer by josgarithmetic(39617)

Question 898053: y=-2x+7

Click here to see answer by Fombitz(32388)

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