Added Moscow Puzzles

Misc/Moscow Puzzles/problems/239.tex

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+\documentclass[../main.tex]{subfiles}
+
+\begin{document}
+
+	\problem{One Hundred and Fourty-Five Doors}
+
+	Volodya asked, ``What plane did you fly during the air parade?'' His father sketched a formation of 9 planes.
+
+	\begin{figure}[h]
+		\centering
+		\includegraphics[width=9cm]{239}
+	\end{figure}
+
+	``The number of planes to the right of me multiplied by the number of planes to the left of me is 3 less than it would have been if my plane had been 3 places to the right of me.'' How did Volodya solve the problem?
+
+\end{document}