\[\left( \frac{4a^{- 8}}{5b^{- 3}} \right)^{- 2} \cdot 8a^{- 10}b^{9} =\]
\[= \left( \frac{5}{4} \right)^{2}\frac{a^{16}}{b^{6}} \cdot 8a^{- 10}b^{9} =\]
\[= \frac{25}{16} \cdot 8a^{6}b^{3} = \frac{25}{2}a^{6}b^{3} =\]
\[= 12,5a^{6}b^{3}.\]