Let $f(x) = {-5} x + C$, where $C$ is any real number. Then the expression $$\frac{f(x + h) - f(x)}{h}$$ can be written in the form $Ah + Bx + D$, where $A$, $B$, and $D$ are constants. (Note: It's possible for one or more of these constants to be 0.) Find the constants.

$A =$

$B =$

$D =$

Use your answer from above to find $f'(x)$.

$f'(x) =$