Hello!
You first add all the numbers in the ratio
3 + 2 + 1 = 6
Divide the amount of Rupees by the number we got
900 / 6 = 150
You multiply the numbers in the ratio by this number
3 * 150 = 450
2 * 150 = 300
1 * 150 = 150
Rohit will get 450
Raju will get 300
Rupesh will get 150
Hope this helps!