The area of triangle $ABC$, shown here, is $36a^8b^4$ $\text{units}^2$, and its height, $h$, is $ab$ units. In units, what is the length of side $AC$ in terms of $a$ and $b$?

Area = 36a^8b^4

Height = ab

Area = (1/2) AC ( height)

2 *Area / (height ) = AC

2 (36a^8b^4) / (ab) = AC

72 a^7 b^3 = AC