Lorena is trying to determine the velocity of her race car. She went 20 meters east, turned around, and went 40 meters west. She turned the car one more time
and went 35 meters east. This took 4 seconds. What was her velocity?

3.75m/s

Explanation:

Velocity of a body is its displacement divided by time taken;

     Velocity  =  

Displacement is the distance from the starting point.

 Here:

                                                    ------------------------------------------- 20m

   40m ------------------------------------------------------------------------------

           --------------------------------------------------------------------35m

 Displacement  = 35m  - 20m = 15m

   Time taken = 4s

  Velocity  =    = 3.75m/s

it doesn't. it was imagined up in the middle ages.