.
The cost of the meal was 10 euros each, and so they handed over 30e to the waitress (being too mean to include a tip
)
The bar patron decided that to have Agreeables in his bar was an honour
, so he told the waitress that they should have a discount. He decided that she should return 5e to the trio.
As she could not divide the 5e by 3, she decided to give them 1e each
and keep the other 2e herself. 
This means they paid 27e and the waitress had 2e, making a total of 29e.
Where is the missing euro
