A karate studio charges $35 for the first course and $22.50 for each course after that, even if the student leaves the course early. Cena paid $170 for her son to take courses. How many courses did he

A karate studio charges $35 for the first course and $22.50 for each course after that, even if the student leaves the course early. Cena paid $170 for her son to take courses. How many courses did he take? 6 courses 7 courses 8 courses 10 courses