using definition of derivative

using definition of derivative

$f(x)=x^3-6x^2+9x-5$ is given.

What is the value of $$\lim_{h\to0}\frac{[f'(1+2h)+f'(3-3h)]}{2h}$$
I tried to use the definition of derivative,and here it seems like the
expression will be equal to something like the 2nd derivative of $f(x)$
but I'm confused with $2h$ and $-3h$.