The question is: What is the maximum rectangular area that can be enclosed by 120m of fencing if one of the sides of the rectangle is an existing wall (Show algebraically.)

Then there is a drawing of a box, something like this:

I'm not quite sure where to begin; my math "teacher" went over 'y=a(x-h)

^{2}+k' with me, and I sort of got that but now I'm stuck again (see, new problem, needs new example LOL). So far all I've got is:

A=LxW

L=120-2x

W=x

A=(120-2x)(x)

And I doubt that's even close to being on the right planet, let alone the right track.

:(

I think that's everything (for now)...

Thanks so much for any tips.