A group of students are taking Math, Psychology, and History: 20 students are taking Math 17 students are taking Psychology 15 students are taking History 9 students are taking Math & Psychology 8...

A group of students are taking Math, Psychology, and History:

20 students are taking Math

17 students are taking Psychology

15 students are taking History

9 students are taking Math & Psychology

8 students are taking Math & History

6 students are taking Psychology & History

3 students are taking all three classes

How many students are in the group?

There are ___ students in the group.