\(\frac{-11^5.13^7}{11^5.13^8}=\frac{\left(-1\right).11^5.13^7}{11^5.13^7.13}=\frac{-1}{13}\)
\(\frac{2^{10}.3^{10}-2^{10}.3^9}{2^9.3^{10}}=\frac{2^{10}.\left(3^{10}-3^9\right)}{2^9.3^{10}}=\frac{2^9.2.3^9.\left(3-1\right)}{2^9.3.3^9}=\frac{2.2}{3}=\frac{4}{3}\)
a, \(\frac{-11^5.13^7}{11^5.13^8}=\frac{-1}{13}\)
b, \(\frac{2^{10}.3^{10}-2^{10}.3^9}{2^9.3^{10}}=\frac{2^{10}.3^9.\left(1-3\right)}{2^9.3^{10}}=\frac{-4}{3}\)