In a class of 40 students, everyone has either a pierced nose or a pierced ear. The professor asks everyone with a pierced nose
to raise his or her hand. Eight hands go up. Then the professor asked everyone with a pierced ear to do likewise. This time there are 35 hands raised. How many students have piercings both on their ears and their noses?
If everyone in the class has either a pierced nose or ear, we just simply have to add up the total number of hands raised and minus the number of students in the class.
35+8=43
43-40=3
3 students have both a pierced nose and pierced ear.
