Draw a vertical line from the x-axis at the point time = 2 seconds so that it intersects the line representing the velocity of the car. Draw a second vertical line from the x-axis at the point time = 4 seconds so that it intersects the line representing the velocity of the car.

Calculate the area represented by the rectangle enclosed by the two vertical lines you just drew, the line for the velocity of the car, and the x-axis. An example is shown as the blue shaded area in figure