Question

A personal trainer designs exercise plans based on a combination of strength-training and aerobic exercise. A beginner plan has 15 minutes per session of strength-training and 20 minutes per session of aerobic exercise for a total of 90 minutes of exercise in a week. An advanced plan has 20 minutes per session of strength-training and 30 minutes of aerobic exercise for a total of 130 minutes of exercise in a week. Which statement describes when the plans are based on the same number of aerobic exercise sessions?
A. Each plan utilizes a combination of 2 strength-training sessions and 2 aerobic exercise sessions per week.

B. Each plan utilizes a combination of 2 strength-training sessions and 3 aerobic exercise sessions per week.

C. Each plan utilizes a combination of 3 strength-training sessions and 2 aerobic exercise sessions per week.

D. Each plan utilizes a combination of 3 strength-training sessions and 3 aerobic exercise sessions per week.

Answer 1

"Each plan utilizes a combination of 2 strength-training sessions and 2 aerobic exercise sessions per week." because. 
Let n be the number of aerobic and strength-training exercises per week.
Let x be the number of strength-training exercises per week on the beginner  

15x + 20n = 90 

Let y be the number of strength-training exercises for  week on the advanced plan.
20y + 30n = 130 

Multiply both sides by 1.5, to get:
22.5x + 30n = 135 
Subtracting equation 2 from 3 we get:
22.5x - 20y = 5 

Answer 2

The answer is B
Hope this helps:)