AHSME 1961 Problem 15

If $x$ men working $x$ hours a day for $x$ days produce $x$ articles, then the number of articles (not necessarily an integer) produced by $y$ men working $y$ hours a day for $y$ days is: $\textbf{(A)}\ \frac{x^3}{y^2} \textbf{(B)}\ \frac{y^3}{x^2} \textbf{(C)}\ \frac{x^2}{y^3} \textbf{(D)}\ \frac{y^2}{x^3} \textbf{(E)}\ y$