OK, I need help with two pretty basic questions. I keep making the same stupid mistakes. Please help!

Solve to the smallest equation.

1.(a-b)c^{2}+ (b-a)c^{4}

My working out so far:

= c^{2}[(a-b)+(b-a)c^{2})]

... then I don't know what to do. I know the answer is c^{2}(a-b), but how do I get there?

2.(x-y)^{2 }-z^{2}/ (x+z)^{2 }-y^{2 So it occurs to me to use those math equations like following: }x^{2}+2xy +y^{2}-z^{2}/ x^{2}+ 2xz + z^{2}-y^{2 }And then what? I'm not very good at maths...