1951 AHSME Problem 2

A rectangular field is half as wide as it is long and is completely enclosed by x yards of fencing. The area in terms of x is:

(\textbf{A})\ \frac{x^2}2 \qquad (\textbf{B})\ 2x^2 \qquad (\textbf{C})\ \frac{2x^2}9 \qquad (\textbf{D})\ \frac{x^2}{18} \qquad (\textbf{E})\ \frac{x^2}{72}

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.