Concept: The question tests on the basic concepts of Set theory
Solution:
Let the total number of Students = x
Total = A + B - (A ∩ B) + (A U B)'
Total = Students who passed in Math + Students who passed in Science - Students who passed in both + Students who failed in both.
x = 0.7x + 0.75x - 0.65x + 60
x + 0.65x - 0.7x - 0.75x = 60
0.2x = 60
x = 300
Option C