Use the four$-$step process to find the slope of the tangent line to the graph of the given function at

$f(x)=3-6x$

Step $1$:

$f(x+h)=3-6x-6h$

Step $2$:

$f(x+h)-f(x)=-3-6x-6h$

Step $3$:

$\frac{f(x+h)-f(x)}{h}=$

$$

Step $4$: $,f^{\text{'}}(x)=\underset{h0}{lim}\frac{f(x+h)-f(x)}{h}=-6$