Using the properties of logarithms,

$\displaystyle{\log}_{{{5}}}\frac{{y}}{{{{125}}^{{x}}}}\usepackage{cmbright}\Huge\$ can be rewritten as $\displaystyle{\log}_{{{5}}}{y}-?\usepackage{cmbright}\Huge\$ .

The question mark stands for _____.

(Your answer should be simplified and not have a log in it.)