Now let's actually input the function itself. So our volume is equal to x times 20 minus 2x times 30 minus 2x. And that looks about right, so now I think we can graph it. So second, and I want to select that up there, so I'll do graph. And it looks like we did get the right range. So this tells us volume is a function of x between x is 0 and x is 10. And it does look like we hit a maximum point right around there.