Out of 100 students, 50 failed in English and 30 in Mathematics. If 12 students fail in both English and Mathematics. Then the number of students who passed in both the subjects is__________?

A. 26
B. 28
C. 30
D. 32
Explanation:
Let A = Set of students who fail in English
B = Set of students who fair in mathematics
Then , n(A) = 50, n(B) = 30 and n(A∩ B) = 12.
n(AUB) = n(A) + n(B)- n(A∩B) = (50 + 30 -12) = 68
Number of students who fail in one or both the students = 68
Number of those who pass in both = (100 – 68) = 32