Paytrust.com is an online bill paying service that charges $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 that period.

Let x no. of bills were paid by thomas

total amount paid = 5*6 + .5x

=> 48.5 = 30 + .5x

=> x/2 = 18.5

=> x = 37