Correct. Apply the exponent to each factor in parentheses: $\displaystyle{{\left(-{3}\right)}}^{{3}}{{\left({{x}}^{{2}}\right)}}^{{3}}{{\left({y}\right)}}^{{3}}\usepackage{cmbright}\Huge\$

Simplify using the Power Rule: $\displaystyle-{27}{{x}}^{{{2}\cdot{3}}}{{y}}^{{3}}=-{27}{{x}}^{{6}}{{y}}^{{3}}\usepackage{cmbright}\Huge\$