A 9th grade circuit analysis question, help would be appreciated!

You are traveling in a car going at a constant speed of 100km/h down a long, straight highway. you pass another car going in the same direction which is traveling at a constant speed of 80km/h. as measured from your car's reference frame this other car is traveling at −20km/h. what is the acceleration of your car as measured from the other car's reference frame? what is the acceleration of the other car as measured from your car's reference frame?

Idon’t quite understand this problem

If there's a small amount of friction between two surfaces, the result could be select all that applya. no movement b. heatc. a little bit of movementd. sliding around