=> A=\(\)\(\frac{5^2.6^9.10+6^5.2^3.15^3}{5^2.6^8.10-2.6^8.10^3}=\frac{5^2.6^9.2.5+6^5.2^3.\left(3.5\right)^3}{5^2.6^8.2.5-2.6^8.\left(2.5\right)^3}\)
\(\Rightarrow A=\frac{5^3.6^9.2+6^5.2^3.3^3.5^3}{5^3.6^8.2-2.6^8.2^3.5^3}=\frac{5^3.6^9.2+\left(2.3\right)^3.5^3}{5^3.6^8.2-2^4.6^8.5^3}\)
\(\Rightarrow A=\frac{5^3.6^8.6.2+6^8.5^3}{5^3.6^8.2-2^4.6^8.5^3}=\frac{5^3.6^8.\left(6.2+1\right)}{5^3.6^8.\left(2-2^4\right)}\)
\(\Rightarrow A=\frac{6.2+1}{2-2^4}=\frac{12+1}{-14}=\frac{13}{-14}\)