I need the answer as soon as possible please

Question

In a class of 30 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 25 hands raised. How many students have piercings both on their ears and their noses?

Answer 1

We are looking for the intersection of the 2 sets

Total (30)= pierced nose(8) + pierced ear(25) - intersection since this has already been counted twice

30= 8 + 25 -x

x=3