At time t=4 hours, both cars stop. What is the distance between car A and B, also state which car is ahead?

Cars A and B are travelling in a straight line. Their velocity versus time graphs are shown in Figure 1. At time t = 0, car A is ahead of car B by 5 km. 70 Velocity (kilometer/hour) 60 50 40 30 20 -10 |+++++ +++++++ +|||||||||||| 0 0.5 1 1.5 I 2 2.5 Time (hours) Figure 1 3 3.5 4 4.5 A B Cars A and B are travelling in a straight line. Their velocity versus time graphs are shown in Figure 1. At time t = 0, car A is ahead of car B by 5 km. 70 Velocity (kilometer/hour) 60 50 40 30 20 -10 |+++++ +++++++ +|||||||||||| 0 0.5 1 1.5 I 2 2.5 Time (hours) Figure 1 3 3.5 4 4.5 A B