英语翻译Mr Knight was the manager of a hotel .One weekend all of

英语翻译
Mr Knight was the manager of a hotel .One weekend all of the hotels in the city were full because there was a large meeting.On Friday night ,three men came into the hotel and asked for rooms .He explained that because of the meeting ,there were no rooms ready for use .The men were very unhappy because they had no place to stay.He wanted to help them.He remembered that Room418,a very small room upstairs,was empty .He asked the men if they would share it.The three men said they would.
He said that he rent would be thirty dollars .Each man should only pay ten.The men agreed,paid the money and went up to the room.
He soon began to feel sorry ."Thirty dollars id too much for that small room,"he thought,’I should give them a discount ."
He called hid assistant over and said ,"Here's five dollars .Give it to the men in Room418.I've asked them too much money for that small room."
The assistant took the money .While he was on the way to Room418,he started to think,"How can three men divide five dollars I'll give each of them only one dollar and keep two dollars for myself.The men will be happy enough to get anything back.I'll take a little money and Mr.Knight will never know .‘So the assistant returned one dollar to each man .
Now the puzzle is :Each man had at first paid ten dollars .When each got one dollar back from the assistant ,it means each man had actually paid only nine dollars.There were three men .$9乘3=$27.The assistant kept $2.$27+$2=29.Where is missing dollar