write and solve the system of equations to find the number of packages of each type of cheese purchased

Question

The Tran family is bringing 12 packages of cheese to the neighborhood picnic. Sliced cheese is $2.00 per package. Chunk cheese cost $1.50 per package. They spent $20.00 for cheese.

Answer 1

First identify the quantities involved

let S = number of packages of sliced cheese

let C = number of packages of chunk cheese

what formulas relate these quantities?

total number of packages = 12, so 

s + c = 12

total cost = 20 = s*2 + c*1.5

 

I expect that you know how to solve these, but maybe not.

 

s+c=12

2s+1.5c=20

double the first

2S+2c=24

and subtract the second

.5 c = 4

c = 8

substitute and solve for s

s= 4