There are 35 students in a hostel. If the number of students increased by 7, the expense of mess increased by ₹42 per day, while the average expenditure per head decreased by 1. Find the original expenditure of the mess.

₹420

Let original expense per head per day = x

Total number of students = 35

Therefore, original expense per day = 35x

Now, after adding 7 new students;

Total number of students = 42

ATQ,

⇒ 42 (x - 1) = 35x + 42

⇒ 42x - 42 = 35x + 42

⇒ 7x = 84

⇒ x = 12

Original expenditure of mess = 35x = 35 x 12 = 420