"Bill 75 /-" joke

Three friends went to a hotel. the bill was Rs 75/-

each one contributed Rs. 25/-.

the waiter took the bill to the cashier.

the cashier was happy & decided to give them a discount of Rs. 5/- & said the waiter to return them Rs. 5/-.

but he was confused how to distribute Rs 5 among 3 persons.

he kept Rs 2 in his pocket & gave one rupee to each one of the 3 persons.

so 1st each one contributed 25 Rs now as they are given 1 rupee back their contibution reduces to Rs 24.

they all contributed rs 24 that is 24x3=72 & 2 rupees are in the waiters pocket.

the total becomes 74 but they paid rs 75.

where is the remaining 1 rupee?.