problem: Evaluate $\log_{\sqrt8}(64\sqrt{8})$.
solution: Let $x=\log_{\sqrt8}(64\sqrt{8})$. In exponential form this is $64\sqrt8=(\sqrt8)^{x}$. Since $64\sqrt{8}$ can be written as $(\sqrt{8})^5$, we have $(\sqrt{8})^5=(\sqrt{8})^x$. Therefore, $x=\boxed{5}$.