You used the ratio $\displaystyle\frac{{9}}{{5}}\usepackage{cmbright}\Huge\$ in the conversion formula, instead of $\displaystyle\frac{{5}}{{9}}\usepackage{cmbright}\Huge\$ . The correct answer is $\displaystyle{{16}}^{\circ}\text{C}\usepackage{cmbright}\Huge\$ .