There were 35 students in a hostel. If the number of students increases by 7, the expenses of the mess increase by Rs. 42 per day while the average expenditure per head diminishes by Re 1. Find the original expenditure of the mess.	Select:
A) rs . 480	B) rs . 520	C) rs . 420	D) rs . 460	E) none of these

Rationale: let d be the average daily expenditure original expenditure = 35 × d new expenditure = 35 × d + 42 new average expenditure will be : ( 35 × d + 42 ) / 42 = d - 1 on solving , we get d = 12 therefore original expenditure = 35 × 12 = 420 answer : c
Answer: C