Let Surjit invests Rs x.
Then, Charan invests Rs (x + 6,000).
And Nandu invests Rs (x + 6,000 + 4,500).
So, x + x + 6,000 + x + 6,000 + 4,500 = 60,000
3x + 16,500 = 60,000
3x = 43,500
x = 14,500
∴ Nandu : Charan : Surjit
= 25,000 : 20,500 : 14,500 = 50 : 41 : 29
Hence, the required difference
=×18,000=Rs3,150