=\(\dfrac{2^{19}.27^3-15.\left(-4\right)^9.9^4}{6^9.2^{10}+\left(-12\right)^{10}}\)
=\(\dfrac{2^{19}.3^9-2^{18}.3^9.5}{6^9.2^{10}+6^{10}.2^{10}}\)
=\(\dfrac{2^{18}.3^9\left(2-2.5\right)}{6^9.2^{10}\left(1+6\right)}\)
=\(\dfrac{2^{18}.3^9.\left(-8\right)}{3^9.2^{19}.7}\)
=\(\dfrac{-8}{14}=\dfrac{-4}{7}\)