Using the properties of logarithms,

$\displaystyle{\log}_{{{2}}}\frac{{{{64}}^{{x}}}}{{y}}\usepackage{cmbright}\Huge\$ can be rewritten as $\displaystyle?-{\log}_{{{2}}}{y}\usepackage{cmbright}\Huge\$ .

The question mark stands for _____.

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