Question

a car travels 100 meters in 4.0 seconds. Find the average velocity

Answer 1

If you mean in m/s (metres per second), then to work it out you do (distance traveled in metres)/(time taken in seconds) = velocity in metres per second
So inputting what we know
100/4 = Velocity in m/s
Velocity = 25m/s

Answer 2

The velocity can't be found with the given information.  Velocity includes
the direction of motion, and that's not mentioned in the question.

  Average  speed  during the time =

                         (distance covered) / (time to cover the distance) =

                                     (100 m)   /    (4.0 seconds)  =  25 m/s .