the answer is c.
step-by-step explanation:
x is the total time in minutes for the free response
you are given number of questions as 15 - m and time per item as 8 minutes
to find x multiply the two givens together:
x = 8 * (15-m) = 8(15-m)
if you're trying to figure out how much each ounce cost it would be 0.20
cents each ounce