A sum of Rs. 3170 is divided among X, Y and Z such that if Rs. 13, Rs. 12 and Rs. 18 will be diminished from the shares of X, Y and Z respectively, then their shares will be in the ratio 20 : 18 : 21. What is the initial share (in Rs.) of Z?
1
1131
2
1530
3
910
4
1350