Question

Jillian is selling boxes of cookies to raise money for her basketball team. The 10 oz. box costs $3.50, while the 16 oz. box costs $5.00. At the end of one week, she collected $97.50, selling a total of 24 boxes. The system of equations that models her sales is below.

x+ y= 24

3.50x + 5.00y = 97.50

Solve the system of equations. How many 10 oz. boxes were sold?

6
9
12
15

Answer 1

Let x = number of 10‑oz boxes. From x + y = 24, y = 24 − x. Substitute:

3.50x + 5(24 − x) = 97.50
3.50x + 120 − 5x = 97.50
−1.50x = −22.50
x = 15

So 15 ten‑ounce boxes were sold.