Question

In an examination of 140students, 80 passed mathematics, 65 passed physics, 75 passed chemistry, 33 passed both mathematics and physics, while 30 passed mathematics and chemistry only. If 15 students passed all 3 courses and 91 students passed atleast 2 courses. How many students failed all the courses?

Answer 1

Total number of passed students -total student in the examination.
106-140=34ans

Answer 2

91 +15= 106
140 -106=34
34 failed in all the subjects