a: \(=\dfrac{2^{11}\cdot5^7+5^{10}\cdot2^8}{2^8\cdot5^4+5^7\cdot2^5}=\dfrac{2^8\cdot5^7\left(2^3+5^3\right)}{2^5\cdot5^4\left(2^3+5^3\right)}=\left(2\cdot5\right)^3=10^3\)
b: \(=\dfrac{100+121+144}{\left(169+196\right)^2}=\dfrac{365}{365^2}=\dfrac{1}{365}\)