Subtract 32 from both sides: $\displaystyle{F}-{32}=\frac{{9}}{{5}}{C}\usepackage{cmbright}\Huge\$

Multiply both sides by $\displaystyle\frac{{5}}{{9}}\usepackage{cmbright}\Huge\$ to isolate C: $\displaystyle\frac{{5}}{{9}}{\left({F}-{32}\right)}=\frac{{5}}{{9}}\cdot\frac{{9}}{{5}}{C}\usepackage{cmbright}\Huge\$

Simplify to: $\displaystyle\frac{{5}}{{9}}{\left({F}-{32}\right)}={C}\usepackage{cmbright}\Huge\$