how do i solve this

Question

f(x) = x-7, g(x) = x²-5, and h(x) =4-2x

Answer 1

I think there is something missing in your question. Typically, when one is asked to "solve" a system of equations, one is being asked to find the intersection of the equations. However, these 3 do not intersect, so from that perspective, there is no solution. I suspect, however, that you are being asked something else. Take a look at your problem and see what they are asking.

Answer 2

"i have to evaluate (g - f)(x)"

That notation simply means that you subtract the f(x) expression from the one for g(x)

(x^2 - 5) - (x - 7) = x^2 - x + 2

What are we supposed to do with h(x)?