Hello!
They charge $16 dollars a day and he had it for 4 days
16 * 4 = 64
He paid $64 just for having the car
Subtract this from the amount paid
79 - 64 = 15
Divide this number the the cost a mile
15 / 0.15 = 100
He drove 100 miles
The answer is 100 miles
Hope this helps!