Subtract and simplify. Then supply the missing radicand.

$\displaystyle\sqrt{{{300}{{x}}^{{2}}{{y}}^{{2}}}}-{3}\sqrt{{{27}{{x}}^{{2}}{{y}}^{{2}}}}={\left|{x}{y}\right|}\sqrt{?}\usepackage{cmbright}\Huge\$

The missing radicand is _____.