\(\frac{4^6.9^5+6^6.120}{8^4.3^{12}-6^{11}}=\frac{\left(2^2\right)^6.\left(3^2\right)^5+2^6.3^6.2^3.3.5}{\left(2^3\right)^4.3^{12}-2^{11}.3^{11}}=\frac{2^{12}.3^{10}+2^9.3^7.5}{2^{12}.3^{12}-2^{11}.3^{11}}=\frac{2^9.3^7.\left(2^3.3^3+5\right)}{2^{11}.3^{11}.\left(2.3-1\right)}=\frac{221}{2^2.3^4.5}=\frac{221}{1620}\)