BEFORE HOSTING THEIR ANNUAL CHESS TOURNAMENT AND SPELLING BEE, A SC...

7. Before hosting their annual Chess Tournament and Spelling Bee, a school received 7 boxes of honorary medals: one medal for every participant. After the Chess Tournament, two boxes were empty and the rest were still closed. After the Spelling Bee, which had twice as many participants, there were 72 medals left. How many people competed in the Chess Tournament?