Okay, I found this solution by guess and check, but will try to devise a method. For the time being I'll explain how I checked. The car should be traveling at 50 km/h. I found this by starting:

Point A is at 0 km and Point B is at 250 km.

Hour 1 elapses:

Motorcycle at 0 km

Car at 50 km

Hour 2 elapses:

Motorcycle at 75 km

Car at 100 km

Hour 3 elapses: This is the point at which they meet and the motorcycle turns around.

Motorcycle at 150 km

Car at 150 km

Hour 4 elapses:

Motorcycle at 75 km (travelling back to point A)

Car at 200 km

Hour 5 elapses:

Motorcycle at 0 km (Point A)

Car at 250 km (Point B)