2012 Fermat Problem 16

There are 30 people in a room, 60\% of whom are men. If no men enter or leave the room, how many women must enter the room so that 40\% of the total number of people in the room are men?

\textbf{(A)}\ 10\quad \textbf{(B)}\ 6\quad \textbf{(C)}\ 20\quad \textbf{(D)}\ 12\quad \textbf{(E)}\ 15

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