\[2\frac{2}{3}x^{5}y^{8} \cdot \left( - 1\frac{1}{2}x^{3}y^{6} \right)^{2} = 2\frac{2}{3}x^{5}y^{8} \cdot\]
\[\cdot \left( - \frac{3}{2}x^{3}y^{6} \right)^{2} = \frac{8}{3}x^{5}y^{8} \cdot \frac{9}{4}x^{6}y^{12} = 6x^{11}y^{20}\]