Answer:
18 hours
Step-by-step explanation:
First, he worked 3 hours babysitting, so he already made 8*3=24 dollars.
This means he must work 200-24=176 dollars lifeguarding.
Divide that by how much he makes per hour, and 176/15=11.7333 hours lifeguarding.
Round that up if he can't do a fraction of an hour to get 12 hours lifeguarding.
This is possible because the total hours worked is 12+3=15, which is less than 18.
