Acar travels the 120 miles from a to b at 60 miles per hour, and then returns to a on the same road. if the average rate of the round trip is 45 miles per hour, what is the rate, in miles per hour, of the car traveling back from b to a?

Outbound Trip 120 miles 60 mph equals 2 hours

Return Trip 120 miles

Total Trip 240 miles at 45 mph average speed

Total time = distance / rate = 240 / 45 = 5.3333333333 Hours

The return trip of 120 miles takes (5.3333333333 Hours MINUS 2 hours)

Return Trip Speed = 120 / 3.333333333 = 36 miles per hour