Surface Integrals, Stokes & Divergence · Medium problem

Green's theorem gives the area of a region as $\dfrac{1}{2}\oint_C (x\,dy - y\,dx)$. Use it (or the equivalent shoelace sum) to find the area of the quadrilateral with vertices $(0, 0), (4, 0), (4, 2), (0, 5)$ taken in order. Express your answer as a common fraction if needed.