A man has in all Rs. 640 in the denominations of one-rupee, five rupeee and ten rupee notes. the number of each type of notes are equal. What is the total member of notes he has?

A) 90

B) 100

C) 120

D) None of these

Let number of notes of each denomination be x

Then:

x + 5x + 10x = 640

          ⇒ 16x = 640

               ∴ x = 40

 Hence, total number of notes = 3x =3(4) = 120