\(\dfrac{8^5\cdot\left(-5\right)^8+\left(-2\right)^5\cdot10^9}{2^{16}\cdot5^7+20^8}\)
\(=\dfrac{2^{15}\cdot5^8-2^5\cdot10^9}{2^{16}\cdot5^7+20^8}\)
\(=\dfrac{\left(2^{10}\cdot5^{18}-10^9\right)\cdot2^5}{2^{16}\cdot5^7+20^8}\)
\(=\dfrac{\left(2^2\cdot10^8-10^9\right)\cdot2^5}{2^{16}\cdot5^7+20^8}\)
\(=\dfrac{\left(2^2-10\right)\cdot10^8\cdot2^5}{2^{16}\cdot5^7+20^8}\)
\(=\dfrac{\left(4-10\right)\cdot10^8\cdot2^5}{2^{16}\cdot5^7+20^8}\)
\(=\dfrac{-6\cdot10^8\cdot2^5}{2^{16}\cdot5^7+20^8}\)
\(=\dfrac{-3\cdot2\cdot10^8\cdot2^5}{2^{16}\cdot5^7+20^8}\)
\(=\dfrac{-3\cdot2^6\cdot10^8}{2^{16}\cdot5^7+20^8}\)
\(=\dfrac{-3\cdot64\cdot10^8}{2^{16}\cdot5^7+20^8}\)
\(\dfrac{8^5.\left(-5\right)^8+\left(-2\right)^5.10^9}{2^{16}.5^7+20^8}=\dfrac{\left(2^3\right)^5.5^8+\left(-2\right).2^4.2^9.5^9}{2^{16}.5^7+\left(2^2\right)^8.5^8}\) \(=-\dfrac{2^{15}.5^8+2^{14}.5^9}{2^{16}.5^7+2^{16}.5^8}=-\dfrac{2^{14}.5^8.\left(2+5\right)}{2^{16}.5^7.\left(1+5\right)}=-\dfrac{5.7}{4.6}=-\dfrac{35}{24}\)
