Instead of going from four to seven, we're going from seven to four. Well, the key realization is is if you switch the bounds, and this is a key definite integral property, that's going to give you the negative value. So this is going to be equal to the negative of the integral from four to seven of f of x dx. And so this is going to be negative, and we just figured out the integral from four to seven of f of x dx. Well, now that is this area. F of x is above the x-axis. It's a positive area.