Answer:
Let's understand that (gof)(x) is shorthand for g(f(x)). That means replace each x in the function g by f(x).
Now g(x) = x^2, so, replacing x by f(x), we get (gof)(x) = (5x - 4)^2
That's all!
For extra credit, let's try (fog)(x) = f(g(x)) = 5 (x^2) - 4. [Replace every x in f(x) by g(x) = x^2]
