\(\frac{3^6.45^4-3^{10}.45^3}{3^{10}.9.25^3+3^6.45^6}=\frac{3^6.\left(3^2.5\right)^4-3^{10}.\left(3^2.5\right)^3}{3^{10}.3^2.\left(5^2\right)^3+3^6.\left(3^2.5\right)^6}\)
\(=\frac{3^6.3^8.5^4-3^{10}.3^6.5^3}{3^{12}.5^6+3^6.3^{12}.5^6}=\frac{3^{14}.5^4-3^{16}.5^3}{3^{12}.5^6+3^{18}.5^6}\)
\(=\frac{3^{14}.5^3.\left(5-3^2\right)}{3^{12}.5^6.\left(1+3^6\right)}=\frac{3^2.\left(-4\right)}{5^3.730}=\frac{-18}{45625}\)