\[\left( \frac{6x^{- 1}}{y^{- 8}} \right)^{- 4} \cdot \left( 36x^{- 2}y^{7} \right)^{3} =\]
\[= \frac{6^{- 4} \cdot x^{4} \cdot \left( 6^{2} \right)^{3} \cdot x^{- 6}y^{21}}{y^{32}} =\]
\[= \frac{6^{- 4} \cdot 6^{6}x^{- 2}}{y^{11}} = \frac{6^{2}}{x^{2}y^{11}} = \frac{36}{x^{2}y^{11}}\]