Question 976389
I'll do part a) to get you started


f(x) = 5x-7


f(<font color="red">g(x)</font>) = 5(<font color="red">g(x)</font>)-7 ... replace every x with g(x)


f(<font color="red">g(x)</font>) = 5(<font color="red">5-x^2</font>)-7 ... replace g(x) on the right side with 5-x^2 (valid because g(x) = 5-x^2)


f(g(x)) = 5(5-x^2)-7


f(g(x)) = 25-5x^2-7


f(g(x)) = -5x^2+18


Now plug in x = -1


f(g(x)) = -5x^2+18


f(g(-1)) = -5(-1)^2+18 ... replace every x with -1


f(g(-1)) = -5(1)+18


f(g(-1)) = -5+18


f(g(-1)) = 13


I leave part b) for you.