\[\left( - \frac{2p^{4}q^{2}}{5m^{8}} \right)^{3}\ :\left( - \frac{2p^{5}q^{3}}{5m^{6}} \right)^{4} =\]
\[= - \frac{8p^{12}q^{6}}{125m^{24}}\ :\frac{16p^{20}q^{12}}{625m^{24}} =\]
\[= - \frac{8p^{12}q^{6} \cdot 625m^{24}}{125m^{24} \cdot 16p^{20}q^{12}} =\]
\[= - \frac{5}{2p^{8}q^{6}}\]