\(Q=\dfrac{\sqrt{x}-\sqrt{x}+3}{\sqrt{x}\left(\sqrt{x}-3\right)}:\dfrac{x-9-x+4}{\left(\sqrt{x}-2\right)\left(\sqrt{x}-3\right)}\)
\(=\dfrac{3}{\sqrt{x}\left(\sqrt{x}-3\right)}\cdot\dfrac{\left(\sqrt{x}-2\right)\left(\sqrt{x}-3\right)}{-5}\)
\(=\dfrac{-3\sqrt{x}+6}{5\sqrt{x}}\)