UPSC 2017 CDS II Math Paper

Let H and E be the sets of students passing in Hindi and English, respectively.
Suppose the number of students be 100.
Number of students passing in both the subjects
=n(H∩E)
=100−n(H∪E)
=100−(35+45−20)
=100−60
=40
Thus, the percentage of students passing in both the subjects is 40%