Doctor told Raj to drink 8.5 litres of water daily. If Raj drinks 5.25 litres of water in a day then how much liters is he short from doctors prescription?

Total amount of water Raj has to drink = 8.5 L
The amount he already drank = 5.25 L

The remaining amount = 8.5 - 5.25

8.50
- 5.25
__________
3.25

So Raj is 3.25 L short from achieving the 8.5 L mark.