Question

A store is having a sale on walnuts and chocolate chips. For
5
pounds of walnuts and
3
pounds of chocolate chips, the total cost is
$19
. For
7
pounds of walnuts and
9
pounds of chocolate chips, the total cost is
$35
. Find the cost for each pound of walnuts and each pound of chocolate chips.

Answer 1

5w + 3c = 19 ....multiply by -3
7w + 9c = 35
----------------
-15w - 9c = - 57 (result of multiplying by -3)
7w + 9c = 35
---------------add
-8w = - 22
w = -22/-8
w = 2.75

5w + 3c = 19
5(2.75) + 3c = 19
13.75 + 3c = 19
3c = 19 - 13.75
3c = 5.25
c = 5.25/3
c = 1.75

so walnuts (w) cost $ 2.75 per lb and chocolate chips (c) cost $ 1.75 per lb