\(\dfrac{4^6\cdot9^5+6^9\cdot120}{-8^4\cdot3^{12}-6^{11}}\)
\(=\dfrac{2^{12}\cdot3^{10}+2^{12}\cdot3^{10}\cdot5}{2^{12}\cdot3^{12}-2^{11}\cdot3^{11}}\)
\(=\dfrac{2^{12}\cdot3^{10}\cdot\left(1+5\right)}{2^{11}\cdot3^{11}\left(2\cdot3-1\right)}\)
\(=\dfrac{2\cdot6}{3\cdot5}=\dfrac{4}{5}\)