Answer: The correct option is (B) 7.
Step-by-step explanation: Given that 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.
We are to find the number of courses that he took.
Let x represents the number of courses that Cena took.
Then, according to the given information, we have
Thus, the required number of courses that Cena took is 7.
Option (B) is CORRECT.