\[\frac{81^{- 5} \cdot 9^{- 8}}{27^{- 11}} = \frac{\left( 3^{4} \right)^{- 5} \cdot \left( 3^{2} \right)^{- 8}}{\left( 3^{3} \right)^{- 11}} =\]
\[= \frac{3^{- 20} \cdot 3^{- 16}}{3^{- 33}} = \frac{3^{- 36}}{3^{- 33}} = 3^{- 3} =\]
\[= \frac{1}{27}\]