You may have multiplied 4 yards by $\displaystyle\frac{{{12}\ \text{ feet}}}{{{1}\ \text{ yard}}}\usepackage{cmbright}\Huge\$ and then added 2 feet. You need to multiply 4 yards by $\displaystyle\frac{{{3}\ \text{ feet}}}{{{1}\ \text{ yard}}}\usepackage{cmbright}\Huge\$ and then add 2 feet. The correct answer is 14 feet.