I don't undestand why answer 1 11?
I think answer is 6 6 7 8 9 10 11.
Thanks.

The conditions states: "It is assumed that the teacher didn't give extra notes, which means that there would not be enough money for the tickets if any of the notes was taken away."

That means if the smallest banknote (10 rubbles) is taken away, the money would not be sufficient for the amount of tickets she wanted to buy. She wanted 11 tickets, no less.

Thank you for the correct explanation.

Edited by author 12.02.2012 16:58

Edited by author 12.02.2012 16:58