I'm new here, though I wish I had found this forum long ago. (I'm an applied math major.)

I've run into trouble on my homework which is, of course, due tomorrow. Here we go:

If f: A -> B and g: B -> C are one-to-one functions, show that (g o f)^-1 = f^-1 o g^-1 on Range (g o f).

I'm stuck on where to even start on this proof, and it's driving me mad. For the record, the above notation ^-1 denotes "inverse". Please help?