You may have multiplied 5 feet by $\displaystyle\frac{{{1}\ \text{ foot}}}{{{12}\ \text{ inches}}}\usepackage{cmbright}\Huge\$ and then added 3 inches. You need to multiply by $\displaystyle\frac{{{12}\ \text{ inches}}}{{{1}\ \text{ foot}}}\usepackage{cmbright}\Huge\$ and then add 3 inches.