\[\left( \frac{x^{13}y^{- 5}}{c^{6}m^{- 12}} \right)^{- 4} = \frac{x^{- 52}y^{20}}{c^{- 24}m^{48}} = \frac{y^{20}c^{24}}{x^{52}m^{48}}.\]