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