Simplify the expression by writing as a single power and then evaluate for a=-1,b=-2 and c=3.
$$(b^{3}a^{4})^{2} \times (a^{3}c)^{3} \over ac^{3}$$
Here is what I did: $$\begin{align}\frac{(b^{3}a^{4})^{2} \times (a^{3}c)^{3}}{ac^{3}} &=\frac{b^{6}a^{8} \times a^{9}c^{3}}{ac^{3}}\\ &=\frac{a^{17}b^{6}c^{3}}{ac^3}\\ &=a^{16}b^{6}\\ &=(-1)^{16}(-2)^{6}\\ &=(1)(64)\\ &= 64\end{align}$$
I have no answer key, is my answer correct?