SOLUTION: A store is having a sale on walnuts and chocolate chips. For 7 pounds of walnuts and 9 pounds of chocolate chips, the total cost is $37. For 5 pounds of walnuts and 3 pounds of cho

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Question 1203910: A store is having a sale on walnuts and chocolate chips. For 7 pounds of walnuts and 9 pounds of chocolate chips, the total cost is $37. For 5 pounds of walnuts and 3 pounds of chocolate chips, the total cost is $17. Find the cost for each pound of walnuts and each pound of chocolate chips.

Found 2 solutions by Theo, josgarithmetic:
Answer by Theo(13342) (Show Source):
You can put this solution on YOUR website!
x = number of pounds of walnuts.
y = number of pounds of chocolate chips.

7x + 9y = 37
5x + 3y = 17

multiply both sides of the second eqution by 3 and leave the first equation as is to get:

7x + 9y = 37
15x + 9y = 51

subtact both sides of the first equation from both sides of the second equation to get:
8x = 14
solve for x to get:
x = 1.75

replace x with 1.75 in the first equation to get:
7x + 96 = 37 becomes 7 * 1.75 + 9y = 37
simplify to get:
12.25 + 9y = 37
subtact 12.25 from both sides of the equation to gt:
9y = 37 - 12.25 = 24.75
solve for y to get 24.75 / 9 = 2.75

cost of walnuts is 1.75 per pound.
cost of chocolate chips is 2.75 per pound.

7 * 1.75 + 9 * 2.75 = 37
5 * 1.75 + 3 * 2.75 = 17

solution is confirmed to be good.

solution is:
cost of 1 pound of walnutes is 1.75.
cost of 1 pound of chocolate chips is 2.75.

Answer by josgarithmetic(39630) (Show Source):
You can put this solution on YOUR website!
w, walnut price
c, chocolate chips price

Three times equation #2.

Now do E2-E1.

, and you can find the value for c.