First we can figure out an hourly rate at which cars are washed. To do so, we need to divide 5 cars by 3 hours.
Then we need to multiply 7.5 hours by the rate. This will tell us how many cars are washed in 7.5 hours.
= 12.5 cars
Then we need to multiply 7.5 hours by the rate. This will tell us how many cars are washed in 7.5 hours.