Answer
$ ( 4-3x)(9x^2 +12x +16)$
Work Step by Step
Since $64-27x^3$ is a difference of the two cubes $4^3$ and $(3x)^3$, then by making use of the difference of two cubes
$$a^3 -b^3 = (a - b)(a^2 +ab + b^2),$$
we have
\begin{align*}
64-27x^3&=4^3-(3x)^3\\
&= (4-3x)(4^2 +4(3x) + (3x)^2)\\
&= ( 4-3x)(16 +12x +9x^2)\\
&= ( 4-3x)(9x^2 +12x +16)
\end{align*}