A high school class consist of 60 students. Each student may take one or more of tjhe three sports, swimming, squash, and karate, if he wishes. 5 students take no sport at all. Of the 31 who attend swimming 14 take no other sport and 5 take both karate and squash as well. 10 students take only squash and a further 23 take squash plus one or more other sports. Karate as a single sport is taken by 6 students.