Question

Mrs. Boyer is shopping for school supplies with her children. Jesse selected 3 one-inch binders and 3 two-inch binders, which cost a total of $33. Luann selected 2 one-inch binders and 1 two-inch binder, which cost a total of $15. How much does each size of binder cost?

Answer 1

Answer: the cost of 1 one-inch binder is $4

the cost of 1 three-inch binder is $7

Explanation:

Let x represent the cost of 1 one-inch binder.

Let x represent the cost of 1 three-inch binder.

Jesse selected 3 one-inch binders and 3 two-inch binders, which cost a total of $33. This means that

3x + 3y = 33 - - - - - - - - - - 1

Luann selected 2 one-inch binders and 1 two-inch binder, which cost a total of $15. This means that

2x + y = 15 - - - - - - - - - - - 2

Multiplying equation 1 by 2 and equation 2 by 3, it becomes

6x + 6y = 66

6x + 3y = 45

Subtracting, it becomes

3y = 21

y = 21/3 = 7

Substituting y = 7 into equation 2, it becomes

2x + 7 = 15

2x = 15 - 7 = 8

x = 8/2 = 4