Newton’s second law

A 0.20 kg ball is moving horizontally at 6.0 m s⁻¹ towards a wall. It hits the wall and rebounds horizontally in the opposite direction at 2.0 m s⁻¹. The contact time is 0.040 s.

Using Newton's second law in the form $F = \Delta p / \Delta t$, find the average force exerted on the ball by the wall.