When you tally the bill backwards, you add the amount paid and the amount returned. So you add bill=72 & change=3 totaling to 75. You don't add waiter's change 2 as it is included in the 72 you mentioned.
In your logic
"They all contributed Rs 24 -- that is 24x3=72 & 2 rupees are in the waiters pocket."
should read as:
They all contributed Rs 24 -- that is 24x3=72 & 3 rupees was received as change.
"Life is like a bicycle, if it's too easy - you're probably going down :)"
When you tally the bill backwards, you add the amount paid and the amount returned. So you add bill=72 & change=3 totaling to 75. You don't add waiter's change 2 as it is included in the 72 you mentioned.
In your logic
"They all contributed Rs 24 -- that is 24x3=72 & 2 rupees are in the waiters pocket."
should read as:
They all contributed Rs 24 -- that is 24x3=72 & 3 rupees was received as change.
"Life is like a bicycle, if it's too easy - you're probably going down :)"