Paytrust.com is an online bill-paying service that charge $5 per month plus $0.50 per paid bill. Thomas used this service for 6 months and paid a total of $48.50. How many bills were paid through paytrust.com during this period.

Solution:

There are x bills

So

5+0.5x = 48.5

x = 87

So there are 87 bills paid