$$(\frac{125}{8})\times(\frac{125}{8})^{x}=(\frac{5}{2})^{18}$$
$x=5$
$x=\frac{2\pi n_{1}i}{3\ln(\frac{5}{2})}+\frac{\log_{\frac{5}{2}}\left(\frac{30517578125}{32768}\right)}{3}$
$n_{1}\in \mathrm{Z}$
