Chapter 5 - Applications Of The Definite Integral In Geometry, Science, And Engineering - 5.1 Area Between Two Curves - Exercises Set 5.1 - Page 354: 36

See explanation.

Area between the acceleration curve and the acceleration curve The t-axis is the velocity of the car. The difference of these two areas is then the given area $A$ and therefore denotes the difference in velocity between the two cars.