Answer:
I believe the answer would be $100
Explanation:
1. He already payed the $25 so he doesn't need to pay that anymore
2. If he's paying $15 a month you would have to multiply 15 by 5 because he went for 5 months
3. for the five months he payed $75, so after that you would have to add the additional $25 to the $75 get the answer of $100