Incorrect. The area enclosed by the fence has length $\displaystyle{40}+{2}{x}\usepackage{cmbright}\Huge\$ feet and width $\displaystyle{20}+{2}{x}\usepackage{cmbright}\Huge\$ feet. Therefore, this area is $\displaystyle{\left({40}+{2}{x}\right)}{\left({20}+{2}{x}\right)}={1},{500}\usepackage{cmbright}\Huge\$ . Multiply out, rewrite in standard form, divide by 4, and use the Quadratic Formula. The negative solution is impossible, so the positive solution is the correct value.