And to think about what that has to be, we just have to think, what's the total width that we're covering? Well, the total distance here is going to be b minus a. And we're just going to divide by the number of rectangles that we want, the number of sections that we want. So we want to divide by n. So if we assume this is true, and then we assume that a is equal to x0, and then x1 is equal to x0 plus delta x, x2 is equal to x1 plus delta x, and we go all the way to xn is equal to xn minus 1 plus delta x, then we've essentially set up this diagram right over here. b is actually going to be equal to xn. So this is xn. It's equal to xn minus 1 plus delta x.