Respuesta :

just to confirm is it x-5/8 or (x-5)/8
We assume 
[tex]f(x)=\dfrac{x-5}{8}[/tex]
When this is written using plain text, parentheses are required in order to show what the numerator of the fraction is: f(x) = (x-5)/8.

g(f(x)) = g((x-5)/8)
 = 8((x-5)/8) +5
 = (x-5) +5
 = x

g(f(x)) = x