Answer
$-\frac{\sqrt[3]{a}}{3}$.
Work Step by Step
The given expression is
$=\sqrt[3]{\frac{a}{-27}}$
Use quotient property of cube roots.
$=\frac{\sqrt[3]{a}}{\sqrt[3]{-27}}$
Use $-27=(-3)^3$.
$=\frac{\sqrt[3]{a}}{\sqrt[3]{(-3)^3}}$
Simplify.
$=\frac{\sqrt[3]{a}}{-3}$
$=-\frac{\sqrt[3]{a}}{3}$.
