Rabi takes 3 minutes to inspect a car, and Sashi takes 4 minutes ta inspect a car. If they both start inspecting different cars at 8:30 AM , what would be the ratio of the number of cars inspected by Robi and Sashi by 8:54 AM of the same day?

Answer: 
4:3
Rabi takes 3 minutes to inspect a car, and Sashi takes 4 minutes ta inspect a car. If they both start inspecting different cars at 8:30 AM , what would be the ratio of the number of cars inspected by Robi and Sashi by 8:54 AM of the same day?