\[\left( \frac{3x^{2}y^{- 3}}{z} \right)^{2}\ :\frac{(3x)^{3}z^{- 2}}{y^{5}} =\]
\[= \frac{9x^{4}y^{- 6}}{z^{2}} \cdot \frac{y^{5}}{27x^{3}z^{- 5}} =\]
\[= \frac{xy^{- 1}}{3z^{- 3}} = \frac{xz^{3}}{3y}.\]