Ok, I suck at word problems, but I have to get this done. I'm going to post the whole thing, but I probably only need the equation. After that, I should be able to do it.

A rope is to be streched at uniform height from a tree to a fence, 20 feet from the tree, and then to the side of a building, 35 feet from the tree, at a point 30 feet from the fence.

a. If 63 feet of rope is to be used, how far from the building wall should the rope meet the fence?

b.How far from the building wall should the rope meet the fence if as little rope as possible is to be used?

It's not very good, but this is the best I can do:

Again, thanks in advance.