Let f(x)= xsquared-x-4 and g(x) 2x-4

f(x)= x^2-x-4 and g(x) =  2x-4

Find g(8) and f(g(8)).

g(8)  =  2(8)  - 4  =  16 - 4  = 12

So 

f (g(8)  = f (12)  =

(12)^2 - 12 - 4  =

144 - 12  - 4  =

132 - 4  =

128