\[\frac{(5p)^{2} \cdot q^{- 7}}{r^{6}} \cdot \frac{\left( r^{2}q^{3} \right)^{3}}{5p} =\]
\[= \frac{25p^{2} \cdot r^{6}q^{9}}{r^{6}q^{7} \cdot 5p} = 5pq^{2}.\]