Find $G_a(x)$ for $a_n={4^{3n-5}\over3^{2n+4}}$

Question

I don't really know where to begin on this one. I haven't gotten very far but I feel like with a few hints I should at least be able to start solving this.

Answer 1

Hint: $$a_nx^n=\left(\frac{4^{-5}}{3^4}\right)\left(\frac{4^3x}{3^2}\right)^n.$$