$21.50 - $4 = $17.50 If you start with $21.50, subtract the $4 entrance fee, you have $17.50 left to spend on rides. To figure out how many rides you can go on, divide $17.50 by $2.50. You can go on 7 rides. Here's the equation:
(21.5-4)/2.5=amount of rides
(21.5-4)/2.5= 7 rides
