In a group of students, 7 have been to Italy, 12 to France, and 3 to both. How many students are in the group?

In a group of students, 7 have been to Italy, 12 to France, and 3 to both. How many students are in the group?

Solution:

From set theory:

n(A or B)=n(A)+n(B)-n(A and B)

so our total is 7+12-3 which means there are 16 in the group