1. Determine the Displacement:

* The car starts 50 m south of the library and ends up 250 m north of the library.

* This means the total displacement is 50 m (south) + 250 m (north) = 300 m (north).

2. Calculate the Velocity:

* Velocity is defined as displacement divided by time.

* Velocity = Displacement / Time

* Velocity = 300 m / 15 s = 20 m/s (north)

Therefore, the velocity of the car is 20 m/s north.