1971 AHSME Problem 2

If b men take c days to lay f bricks, then the number of days it will take c men working at the same rate to lay b bricks, is

\textbf{(A) }fb^2\qquad \textbf{(B) }b/f^2\qquad \textbf{(C) }f^2/b\qquad \textbf{(D) }b^2/f\qquad \textbf{(E) }f/b^2

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