Answer
$f^{-1}(x)=\frac{2x-4}{x+3}$
Work Step by Step
$f(x)=\frac{-3x-4}{x-2},$
$y=\frac{-3x-4}{x-2},$
a. $x=\frac{-3y-4}{y-2},$
$x(y-2)=-3y-4,$
$xy-2x=-3y-4,$
$xy+3y=2x-4,$
$y(x+3)=2x-4,$
$y=\frac{2x-4}{x+3}=f^{-1}(x),$
b. Domain of $f(x)$ is $x\in\mathbb{R} \ne 2$ and Domain of $f^{-1}(x)$ is $x\in\mathbb{R}\ne -3$