Let A be the set of students who read "Hitavad" and B the set of students who read "Hindustan". From the given information: n(A∪B)=50−10=40. n(A)=30 n(B)=35. By using n(A∪B)=n(A)+n(B)−n(A∩B), we get: 40=30+35−n(A∩B) ⇒n(A∩B)=25 ∴ The number of students who read both "Hitavad" and "Hindustan" newpapers is n(A∩B)=25.