3.4: Related rates for an expanding cube

A cube of side $x\,\mathrm{cm}$ has surface area $S\,\mathrm{cm}^{2}$. The volume $V\,\mathrm{cm}^{3}$ is increasing at $480\,\mathrm{cm}^{3}\mathrm{s}^{-1}$. Find, at the instant when $V = 512$,