Help I don't understand how to do this

Question

Given that f(x) =x^2-8x and g(x)= x+2, calculate



(a) f o g (1)= Correct

(b) g o f (1)= 

(c) f o f (1)= Incorrect

(d) g o g (1)= 

I know I'm not using the "o" correctly but I'm not sure how to put it in.

Answer 1

a) f(g(1))) = f(3) = 1

g(1)=3, f(3)=1

b) g(f(1)) = g(-7) = -5

f(1)=-7, g(-7)=-5

3) f(f(1)) =f(-7) = (-7)^2 - 8(-7)= 49+56= 105

f(1)=-7, f(-7)= 105

d) g(g(1)) =g(3) = 5

g(1)=3, g(3)=5