Juan charges $3.50 per hour for baby-sitting. Write a rule to describe how the amount of money M earned is a function of the number of hours h spent baby-sitting. About how long will it take Juan to earn $15?


A.
M = 3.5h; about 12 hours


B.
M = 3.5h; about 4 hours


C.
h = 3.5M; 53 hours