In an examination 65% students pass in history and 55% students pass in hindi. If 5% students failed in both the subjects, then what is the percentage of students who have passed in both the subjects?

Let the total number of students in the exam be $$100x$$

Now, 65% of the students pass in history, 55% pass in Hindi and 5% failed in both.

=> $$a+b = 65x$$ ------------(i)

$$b+c = 55x$$ -----------(ii)

$$d = 5x$$ -----------(iii)

Adding equations (ii) and (iii), we get :

=> $$b+c+d=60x$$

Also, $$a+b+c+d = 100x$$

=> $$a+60x=100x$$

=> $$a=100x-60x=40x$$

Substituting it in equation (i),

=> $$b = 65x-40x=25x$$

$$\therefore$$ 25% of the students have passed in both the subjects.

=> Ans - (C)