It seems that you overlooked the negative in the exponent. The second factor is $\displaystyle{{3}}^{{-{3}}}\usepackage{cmbright}\Huge\$ which equals $\displaystyle\frac{{1}}{{{3}}^{{3}}}\usepackage{cmbright}\Huge\$

The correct answer is: $\displaystyle\frac{{1}}{{3}}\usepackage{cmbright}\Huge\$