An amount of Rs. 3100 is made up of Rs. 100, 50, 20 and 10 notes. The number of Rs.10 notes are 2 times the number of Rs.20 notes. The number of Rs.20 notes are 2 times the number of Rs.50 notes. The number of Rs.50 notes are 4 times the number of Rs.100 notes. How many Rs.50 notes are there?
