I think you're getting the idea here. Trapezoid 3 is going to be f of 3 plus f of 4, divided by 2 times delta x. And then, let's see, I'm running out of colors. This is trapezoid 4 right over here. So plus f of 4 plus f of 5, all of that over 2 times delta x. And then we have our last trapezoid, which I will do in yellow. So this is trapezoid number 5.