Incorrect. Set the width of the border to x. Find the area of the blanket with the border by multiplying its width $\displaystyle{\left({6}+{2}{x}\right)}\usepackage{cmbright}\Huge\$ by its height $\displaystyle{\left({5}+{2}{x}\right)}\usepackage{cmbright}\Huge\$ -- notice you use +2x since the width x is added to both the left and right sides and the top and bottom of the blanket. You know the area of the border is 12 square feet; set this equal to the difference of the area of the blanket with the border and the area of the blanket without the border.