Assume there is a car at 7 miles from the original place and at rest for 2 minutes
Then it started to move by a constant speed from 7 miles to 5 miles in for minutes (6 - 2)
The constant speed = (7-5)/(6-2) = 2/4 = 0.5 miles/min (back to original position)
Then the car speed is changed from 5 miles to the original position (0 miles) for 2 minutes (8 - 6)
The new constant speed = (5-0)/(8-6) = 5/2 = 2.5 miles/min (back to original position)
It took rest for 6 minutes (14 - 8), then started to move again for 9 miles in 6 minutes (20-14) in the opposite direction
Then the new constant speed = (9-0)/(20-14) = 9/6 = 1.5 miles/min (from the original position)