Long description
The figure shows a set of Cartesian axes labelled x and y concentrated in the upper-right quadrant. There are points a and b labelled on the positive x-axis with a being nearer the origin. An arbitrary curve labelled y equals g of x slopes down from left to right and another arbitrary curve labelled y equals f of x is below the first curve but this one has a shallow local minimum and maximum. Both curves start and finish at point directly above the points labelled a and b. The area under g of x to f of x is shaded. The area under f of x to the positive x-axis is shaded in a darker shade.