Incorrect. Because the problem says "directly proportional," the equation to use is $\displaystyle{y}={k}{x}\usepackage{cmbright}\Huge\$ , where y is the cost and x is the number of square feet. Solve $\displaystyle{165},{000}={k}{\left({2},{200}\right)}\usepackage{cmbright}\Huge\$ for k. Then use this value of k and $\displaystyle{x}={2},{800}\usepackage{cmbright}\Huge\$ in a second direct variation equation, and solve for y.