[tex]\bf \cfrac{27x^2z}{-3x^2z^6}\implies -\cfrac{27}{3}\cdot \cfrac{x^2z}{x^2z^6}\implies -9\cdot \cfrac{x^2x^{-2}}{z^6z^{-1}}\implies -9\cdot \cfrac{x^{2-2}}{z^{6-1}}
\\\\\\
-9\cdot \cfrac{x^0}{z^5}\implies -9\cdot \cfrac{1}{z^5}\implies -\cfrac{9}{z^5}[/tex]