Don't know what I'm doing wrong please help

Let f(x) = - By _ and g(x) = v 8x + 8. Determine the rule for the composite functions fog and go f. (f o g) ( x ) = X (go f) ( x ) = 3.16 X 6. [-/1 Points] DETAILS MY NO Let f(x) = 5x - 6. Simplify each of the following expressions. f(a ) = F(a + h ) = 4 f(a + h) - f(a ) = (Make sure to expand and combine like terms.) f(a + h) - f(a ) ( Make sure to cancel out the factor of h in the denominator.)