Incorrect. Set the width of the border to x. Find the area of the flag (with border) by multiplying its width $\displaystyle{\left({2}+{2}{x}\right)}\usepackage{cmbright}\Huge\$ by its height $\displaystyle{\left({1}+{2}{x}\right)}\usepackage{cmbright}\Huge\$ . Now set the area of the border, 10 square feet, equal to the difference of the flag (with border) and the area of the flag without border $\displaystyle{\left({2}\cdot{1}\right)}\usepackage{cmbright}\Huge\$ . Then simplify your expression to find your trinomial.