\[4\frac{1}{6}a^{8}b^{5} \cdot \left( - 1\frac{1}{5}a^{5}b \right)^{3} = \frac{25}{6}a^{8}b^{5} \cdot\]
\[{\cdot \left( - \frac{6}{5} \right)}^{3}a^{5 \cdot 3}b^{3} = - \frac{25 \cdot 216}{6 \cdot 125}a^{8 + 15}b^{5 + 3} =\]
\[= - \frac{36}{5}a^{23}b^{8} = - 7,2a^{23}b^{8}\]