An international anime fan club surveyed 200 of its members regarding their viewing
habits over the long weekend: 120 watched Psycho-Pass, 90 watched Demon Slayer, 70 watched
My Hero Academia, 40 watched Psycho-Pass and Demon Slayer, 50 watched Psycho-Pass and
My Hero Academia, and 20 watched something else entirely.
a.
How many of the club members watched exactly one show?
b. What percentage of members watched all three anime?