\[\left( 2\frac{1}{3}a^{4}b^{8} \right)^{3} \cdot \left( - 1\frac{2}{7}a^{5}b^{12} \right) =\]
\[= - \frac{9}{7} \cdot \left( \frac{7}{3} \right)^{3} \cdot a^{12}b^{24} \cdot a^{5}b^{12} =\]
\[= - \frac{3^{2} \cdot 7^{3}}{7 \cdot 3^{3}}a^{17}b^{36} = - \frac{7^{2}}{3}a^{17}b^{36} =\]
\[= - \frac{49}{3}a^{17}b^{36} = - 16\frac{1}{3}a^{17}b^{36}\]