Answer
-9x$y^{2}$ + 12$x^{2}$$y^{3}$
Work Step by Step
$\frac{9x^{2}y^{3} - 12x^{3}y^{4}}{-xy}$ =
RECALL:
$\frac{b^{n}}{b^{m}}$ = $b^{n-m}$
So, $\frac{9x^{2}y^{3} - 12x^{3}y^{4}}{-xy}$ = $\frac{9x^{2}y^{3}}{-xy}$ + $\frac{-12x^{3}y^{4}}{-xy}$ =
-9x$y^{2}$ + 12$x^{2}$$y^{3}$
