So this is the curve, or it's a pretty good approximation of the curve of f of x plus g of x. Now an interesting question is, is what would be, well, we know how we can represent this area. So the area under the curve, f of x plus g of x, above the positive x-axis, between x equals a and x equals b, we know we can represent that as, let me see, I have not used pink yet. So this area right over here, we know that that could be represented as the definite integral from a to b of f of x plus g of x dx. Now the question is, how does this thing relate to d, or how does this area relate to these areas right over here? Well, the important thing to realize is this area that we have in yellow, that's going to be this area right over here. That one's pretty clear.