Simplify: (12a^4b^5)^3

$\frac{(12a^4b^5)^3}{(12a^6b^8)^8}$

$=\frac{1728a^{12}b^{15}}{1728a^{48}b^{64}}$

$=\frac{1}{a^{36}b^{49}}$

1 / (12^5 a^36 b^49)