Alright guys... So I was given a problem on a test for extra credit, but couldn't solve it. Regardless, I won't let it go. So here it is:

You are given a narrow piece of wood that is 90cm long. You want to split the 90cm of wood into 4 pieces so as to make a rectangular frame.

Let x be the length of a short side of the rectangle. Then x is also the length of a short piece of wood.

Write an expression for the length of a long side, then a function of x that gives the rectangles area.

Now I got this: l= 45-x, but I'm pretty sure it is wrong because it doesn't fit into the function for the area. I think a formula for maximum volume would help, but I can't remember it.

Anyway, I would really appreciate it if someone could show me how to find the long side. Thanks!