+218 At the Fitness Center last Monday evening, 17 people wore red shirts, 15
wore watches and 20 played volleyball. Also: Exactly 8 red-shirted
people wore watches. Exactly 13 red-shirted people played volleyball.
Exactly 12 watch-wearers played volleyball. Exactly 5 people playing
volleyball wore both a red shirt and a watch. From this information,
the least number of people that could have been at the Fitness Center last
Monday is?
