\(=\frac{2^{12}\cdot3^{10}+2^9\cdot3^9\cdot2^3\cdot5\cdot3}{2^{12}\cdot3^{12}-2^{11}\cdot3^{11}}\)
\(=\frac{2^{12}\cdot3^{10}\left(1+5\right)}{2^{11}\cdot3^{11}\left(2\cdot3-1\right)}\)\(=\frac{2^{13}\cdot3^{11}}{2^{11}\cdot3^{11}\cdot5}=\frac{4}{5}\)
\(B=\frac{4^6.9^5+6^9.120}{8^4.3^{12}-6^{11}}\)
\(B=\frac{2^{12}.3^{10}+2^9.3^9.2^3.3.5}{2^{12}.3^{12}-2^{11}.3^{11}}\)
\(B=\frac{2^{12}.3^{10}+2^{12}.3^{10}.5}{2^{12}.3^{12}-2^{11}.3^{11}}\)
\(B=\frac{2^{11}.3^{10}.\left(2+2.5\right)}{2^{11}.3^{10}.\left(2.3^2-3\right)}\)
\(B=\frac{2+2.5}{2.3^2-3}\)
\(B=\frac{4}{5}\)
