A tennis ball of mass 50g is hit against a wall. It hits the wall going right at 5 ms^-1 and rebounds to the left at 4 ms^-1, changing its momentum by 0.45 kg m/s left. The ball is in contact with the wall for 0.2 s and experiences an average force of 2.25 N left (applied by the wall).

What is the force of the ball on the wall?