In a class, Anjali ranked eighteen from the top and thirty-ninth from the bottom among those, who passed an examination. Ten students did not appear in the examination and four failed. What is the total number of students in the class?

70

Total pass  =  Left + Right – 1

=  39 + 18 – 1

Total pass  =  56

⇒ 56 + 10 (not appear) + 4 (failed)

⇒ 56 + 10 + 4

⇒ 70