
A mouse (or a person) wants to walk from A to B and he must go right or up (east or
north). How many routes are there possible?
The table above shows the number of students in three clubs at McAuliffe School.
Although no student is in all three clubs, 10 students are in both Chess and Drama, 5
students are in both Chess and Math, and 6 students are in both Drama and Math. How
many different students are in the three clubs?