physics help needed!?

Question

a crash test car has a mass of 1700 kg, it collides with the wall with a velocity of 25 m/s, it then bounces off the wall with a vel.of 12.6 m/s. if the collision takes.25 s to occur, find the impulse of the car due to the collision, and the magnitude of the average force exerted on the car.

Answer 1

Impulse = delta p = 63920 kg m/s

Average force = Impulse/time = 255680 N