Billy and Alvin have summer jobs selling newspaper subscriptions door-to-door, but their compensation plans are different. Billy earns a base wage of $15 per hour, as well as $3 for every subscription that he sells. Alvin gets $4 per subscription sold, in addition to a base wage of $10 per hour. If they each sell a certain number of subscriptions in an hour, they will end up earning the same amount. How many subscriptions would that be?Write a system of equations, graph them, and type the solution.