Find my 1 Rupee!

Three friends went to a restaurant.They have had dinner of Rs.75/-. So each of them had paid Rs.25 to the waiter to give it to the cash counter.The Owner of the restaurant gave them a concession of Rs. 5. From that the waiter took Rs.2 and gave them Rs.3 back. From that each of them take Rs. 1.That means they gave 24 rs each.So the total is (24+24+24)=72 and the waiter take Rs. 2. Sothe total is 72+2=74. But at first they gave Rs. 75. So what happened to one rupee?

Rs given by each friend -
24 * 3= 72
The shopkeeper keeps Rs. 70 & waiter keeps Rs. 2. So 70 + 2=72,
Which is equal to the Rs given by all the friends.

We have to subtract Rs 2 of waiter from 72 because it includes that; then it will become 72-2=70 (which is the actual bill).