Answer
The inequality is
$y\lt\frac{-x}{3}-3$
Work Step by Step
$-3y-x\gt9$
We add x on both sides
$-3y\gt9+x$
We divide both sides by -3 and since we divide by a negative the signs flip.
$y\lt\frac{9+x}{-3}$
$y\lt\frac{-x}{3}-3$