How do you get 0.8 m/s in the -x direction?

A car weighing 13.6 kN is moving at 10.0 m/s in the +x-direction when it collides head-on with a van weighing 33.0 kN. The horizontal force exerted on the car before, during, and after the collision is shown in Fig. 7.7. What is the car's velocity just after the collision? Fx ( KN) 0 -20 -40 -60 0 0.20 0.40 0.60 0.80 1.00 t (s) Figure 7.7 Varying force on a car during a car-van collision. Answer 0.8 m/s in the -x-direction