1952 AHSME Problem 17

A merchant bought some goods at a discount of 20\% of the list price. He wants to mark them at such a price that he can give a discount of 20\% of the marked price and still make a profit of 20\% of the selling price.. The per cent of the list price at which he should mark them is:

\textbf{(A) \ }20 \qquad \textbf{(B) \ }100 \qquad \textbf{(C) \ }125 \qquad \textbf{(D) \ }80 \qquad \textbf{(E) \ }120

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