For your phone calls, you can either A) buy a prepaid monthly plan, or B) pay as you go. A cost $50 per month and calls are free up to 8hrs. Any extra min for that month will cost you $.25. B has a cost of $.15 per minute. What are the two total cost if you plan to talk for 5 hours? and for 9 hours?

How can i make an equation out of this?

5 hours, A = $50, B = .15 * 5 * 60

9 hours, A = 50 + .25*60, B .15 * 9 * 60