Question

A clothing store is having a sale on shirts and jeans. Four shirts and two pairs of jeans cost $78. Three shirts and five pairs of jeans cost $111. The system of equations

4s + 2j = 78
3s + 5j = 111
models this situation, where s is the cost of a shirt and j is the cost of a pair of jeans. How much does one shirt and one pair of jeans cost?

Answer 1

One shirt is $12 and one pair of jeans is $15

Explanation:

Solve by elimination by multiplying the top equation by 3 and the bottom equation by -4:

12s + 6j = 234

-12s - 20j = -444

Add these together, and solve for j:

-14j = -210

j = 15

So, a pair of jeans is $15. Plug in 15 as j into one of the equations and solve for s:

3s + 5j = 111

3s + 5(15) = 111

3s + 75 = 111

3s = 36

s = 12

One shirt is $12 and one pair of jeans is $15.