 (\frac{m^{-4}}{10n^{5}k^{2}})^{-2}:(5m^{2}n^{3}k)^{3}= \frac{m^{8}}{10^{-2}n^{-10}k^{-4}*5^{3}m^{6}n^{9}k^{3}}= \frac{10^{2}m^{2}}{5^{3}n^{-1}k^{-1}}= \frac{4}{5}m^{2}nk   