You need to first apply the order of operations to the numerator and then divide.

$\displaystyle\frac{{{{\left({3}-{{3}}^{{2}}\right)}}^{{2}}}}{{{3}}}=\frac{{{{\left({3}-{9}\right)}}^{{2}}}}{{{3}}}=\frac{{{{\left(-{6}\right)}}^{{2}}}}{{{3}}}=\frac{{36}}{{3}}={12}\usepackage{cmbright}\Huge\$