Now, suppose a car travels 90. meters due north in 15 seconds. Then the car turns around and travels 40. meters due south in 5.0 seconds. What is the magnitude of the average velocity of the car during this 20.-second interval?
This question is rather vague
The car travels a total 130 m in 20seconds = 6.5 m/s OVERALL
As far as it's DISPLACEMENT is concerned , it is 90 - 40 meters from the starting point = 50 meters in 20 s = 2.5 m/s NET