A person Can travel 120 miles in one direction. the return trip was accomplished at double the speed and took three hours less time. Find the speed going.

40 mph would be 120 miles in 3 hours (120/40)

80 mph is 120 miles in 1.5 hours (120/80)

3 - 1.5 = 1.5, not 3 hrs

Change the speed to 20 mph (1/2 the speed) to double the hours.

20 mph = 6 hours (120/20)

40 mph = 3 hrs (120/40)

6 - 3 = 3 hours difference