I'm not going to work all your problems for you but this is how you do it:

think of f(g(x)) = 1/(-2x + 5) and g(f(x)) = -2(1/x) + 5.

Example:

If f(x) = 2x and g(x) = 3x and h(x) = 4x

then f(g(x)) = 2( 3x ) and f(h(x)) = 2( 4x)

similarly g(f(x)) = 3( 2x ) and g(h(x)) = 3( 4x )

as well as f(x)g(x) = (2x)(3x)

Whatever is inside the parenthesis is what you place as x for the equation. If f(x) = 2x and they ask you to evaluate f(2) then its just simply 2(2) and g(5) = 3(5).

Hope this helps