Ta có: \(\frac{9^9.225^5.8^7}{18^{12}.625^3.24^3}\)=\(\frac{\left(3^2\right)^9.\left(25.3^2\right)^5.\left(2^3\right)^7}{\left(2.3^2\right)^{12}.\left(25^2\right)^3.\left(3.8\right)^3}\)
=\(\frac{3^{18}.25^5.3^{10}.2^{21}}{2^{12}.3^{24}.25^6.3^3.2^9}\)
=\(\frac{3^{28}.25^5.2^{21}}{3^{27}.25^6.2^{21}}\)=\(\frac{3}{25.}\)