Answer
$log_{\frac{1}{6}}216=-3$
Work Step by Step
For all positive numbers $a$, where $a\ne1$, and all positive numbers $x$, we know that $y=log_{a}x$ means the same as $x=a^{y}$.
Therefore, $(\frac{1}{6})^{-3}=216$ means the same as $log_{\frac{1}{6}}216=-3$.