Tutors Answer Your Questions about Linear-systems (FREE)
Question 192256: An office has some 20 cent stamps and some 28 cent stamps. All together the office has 140 stamps for a total value of $31.20. How many of each stamp does the office have?
my try:
Stamps Number Value Total Value
20 cent x .20 .20x
28 cent 140 -x .28 .28(140-x)
.20x + .28(140-x) = 31.20
.20x + 39.20 - .28x = 31.20
.08x + 39.20 = 31.20
-.08x = -8.00
x = 1
WRONG? What am I doing wrong?? Help!
Click here to see answer by Mathtut(3670)  |
Question 192256: An office has some 20 cent stamps and some 28 cent stamps. All together the office has 140 stamps for a total value of $31.20. How many of each stamp does the office have?
my try:
Stamps Number Value Total Value
20 cent x .20 .20x
28 cent 140 -x .28 .28(140-x)
.20x + .28(140-x) = 31.20
.20x + 39.20 - .28x = 31.20
.08x + 39.20 = 31.20
-.08x = -8.00
x = 1
WRONG? What am I doing wrong?? Help!
Click here to see answer by radikrr(7) |
Question 192373: You decide to design and sell customized t-shirts. the company charges you $7.50 for each t-shirt and a set-up cost of $22.50 for a new design. You decide to sell the t-shirts for $8.25 each.
A. Write an equation that gives the production cost in dollars to make one design of t-shirt in terms of the number of t-shirts made. Be sure to describe what your variables represent. Use a complete sentence in your answer.
B. Write an equation that gives the income (the amount of money that you earn) in dollars in terms of the number of t-shirts sold. Be sure to describe what your variables represent. Use a complete sentence in your answer.
Click here to see answer by stanbon(75887) |
Question 192373: You decide to design and sell customized t-shirts. the company charges you $7.50 for each t-shirt and a set-up cost of $22.50 for a new design. You decide to sell the t-shirts for $8.25 each.
A. Write an equation that gives the production cost in dollars to make one design of t-shirt in terms of the number of t-shirts made. Be sure to describe what your variables represent. Use a complete sentence in your answer.
B. Write an equation that gives the income (the amount of money that you earn) in dollars in terms of the number of t-shirts sold. Be sure to describe what your variables represent. Use a complete sentence in your answer.
Click here to see answer by RAY100(1637) |
Question 193255: Ziggy's Famous Yogurt blends regular yogurt that is 3% fat with its no-fat yogurt to obtain low-fat yogurt that is 1% fat. How many pounds of regular yogurt and how many pounds of no-fat yogurt should be mixed to obtain 60 pounds of low-fat yogurt.
so far i have vol of high fat=H
vol of low fat= L
0.03*H +0.01(60-H)=60*0.01
0.03H=6H and thats how far I got with the formula this is a ? can't understand or my brain cannot wrap itself around. PLs respond as soon as possible i am thinking Ihave it half way done but just having a hard time completeing it thanks
Click here to see answer by jim_thompson5910(35256) |
Question 193321: The future Teachers of America Club at Paint Branch High School is maaking a healthy trail mix to to sell during lunch. The mix will have three times the number of pounds of raisins as sunflower seeeds. Sunflower seeds cost $4.00 per pound, raisins cost $1.50 per pound. If the group has $34.00 to spend on the raisins and sunflower seeds , how many pounds of each should they buy.
(please solve this problem by using substution)
Click here to see answer by RAY100(1637) |
Question 193333: Please check my work and let me know if I have the right answers, thank you.
Applications of Linear Equations
1. Joe has a collection of nickels and dimes that is worth $6.05. If the number of dimes was doubled and the number of nickels was decreased by 10, the value of the coins would be $9.85. How many dimes does he have?
43 dimes
x * $0.1 + y * $0.05 = $6.05
x * 2 * $0.1 + (y - 10) * $0.05 = $9.85
Solve for x in equation 1
x * $0.1 = $6.05 - y * $0.05
x = $60.5 - $0.5y
Plug into equation 2
($60.5 - $0.5y) * 2 * $0.1 + (y - 10) * $0.05 = $9.85
$12.1 - $0.1y + $0.05y - $0.5 = $9.85
$1.75 = $0.05y
y = 35 nickels
x * $0.1 + 35 * $0.05 = $6.05
$0.1x = $4.30
x = 43 dimes
Confirm result, does
43 * 2 * $0.1 + (35 - 10) * $0.05 = $9.85
$9.85 = $9.85
Yes
2. An express train and a local train both leave Gray’s Lake at 12:00 noon and head for Chicago 60 miles away. The express travels twice as fast as the local and arrives 2 hours ahead of it. Find the speed of each train.
v1 = speed of express train
v2 = speed of local train
v1 = 30 MPH
V2 = 15 MPH
v = d/t (velocity = distance / time)
t = d/v
t1 = 60 miles / 30 MPH
t1 = 2 hours
t2 = 60 miles / 15 MPH
t2 = 4 hours
Does, t1 = t2 - 2
2 hours = 2 hours
Yes
3. Walt made an extra $12,000 last year from a part-time job. He invested part of the money at 7% and the rest at 9%. He made a total of $970 in interest. How much was invested at 7%?
$5500 invested at 7%
x + y = $12,000
x * 0.07 + y * 0.09 = $970
x = $12,000 - y
($12,000 - y) * 0.07 + y * 0.09 = $970
$840 - 0.07y + 0.09y = $970
0.02y = $130
y = $6500 @ 9%, which means x = $5500 @ 7%
Double check, does
$5500 * 0.07 + $6500 * 0.09 = $970
$970 = $970
Yes
Click here to see answer by RAY100(1637) |
Question 193333: Please check my work and let me know if I have the right answers, thank you.
Applications of Linear Equations
1. Joe has a collection of nickels and dimes that is worth $6.05. If the number of dimes was doubled and the number of nickels was decreased by 10, the value of the coins would be $9.85. How many dimes does he have?
43 dimes
x * $0.1 + y * $0.05 = $6.05
x * 2 * $0.1 + (y - 10) * $0.05 = $9.85
Solve for x in equation 1
x * $0.1 = $6.05 - y * $0.05
x = $60.5 - $0.5y
Plug into equation 2
($60.5 - $0.5y) * 2 * $0.1 + (y - 10) * $0.05 = $9.85
$12.1 - $0.1y + $0.05y - $0.5 = $9.85
$1.75 = $0.05y
y = 35 nickels
x * $0.1 + 35 * $0.05 = $6.05
$0.1x = $4.30
x = 43 dimes
Confirm result, does
43 * 2 * $0.1 + (35 - 10) * $0.05 = $9.85
$9.85 = $9.85
Yes
2. An express train and a local train both leave Gray’s Lake at 12:00 noon and head for Chicago 60 miles away. The express travels twice as fast as the local and arrives 2 hours ahead of it. Find the speed of each train.
v1 = speed of express train
v2 = speed of local train
v1 = 30 MPH
V2 = 15 MPH
v = d/t (velocity = distance / time)
t = d/v
t1 = 60 miles / 30 MPH
t1 = 2 hours
t2 = 60 miles / 15 MPH
t2 = 4 hours
Does, t1 = t2 - 2
2 hours = 2 hours
Yes
3. Walt made an extra $12,000 last year from a part-time job. He invested part of the money at 7% and the rest at 9%. He made a total of $970 in interest. How much was invested at 7%?
$5500 invested at 7%
x + y = $12,000
x * 0.07 + y * 0.09 = $970
x = $12,000 - y
($12,000 - y) * 0.07 + y * 0.09 = $970
$840 - 0.07y + 0.09y = $970
0.02y = $130
y = $6500 @ 9%, which means x = $5500 @ 7%
Double check, does
$5500 * 0.07 + $6500 * 0.09 = $970
$970 = $970
Yes
Click here to see answer by solver91311(24713)  |
Question 193338: PROBLEM:
A chemist needs 900 millileters of a 40% acid solution for a chemistry experiments. The chemist combines x milliliters of a 20% acid solution and y milliliters of a 70% acid solution to make 40% acid solution.
a. write a linear system that repesents the situation
Click here to see answer by Mathtut(3670) |
Question 194145: The perimeter of a rectangle is six times the width. If the length were increased by 4 inches and the width were increased by 7 inches, then the perimeter would be 160 inches. What is the width?
P = 2l + 2w
160 = (2l + 4) +(2w +7) When I substitute, it is just a mess.
Click here to see answer by jim_thompson5910(35256) |
Question 194532: I was trying the tutorial and made it to the point where it says just type in the equation to solve it and it just wont solve this is not for school just trying to learn how much solid wrap and printed wrap was sold what i got was
4.00x + 6.00y = 2340
x + y = 480
Click here to see answer by Alan3354(69443)  |
Question 194532: I was trying the tutorial and made it to the point where it says just type in the equation to solve it and it just wont solve this is not for school just trying to learn how much solid wrap and printed wrap was sold what i got was
4.00x + 6.00y = 2340
x + y = 480
Click here to see answer by ankor@dixie-net.com(22740)  |
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