There is a misdirect in the problem when it says that when you do the math each man paid $9 each for the room, plus $2 tip. They don't. They pay a combined price of $25.00 plus the $2 tip. The problem sets up a set of facts:
* $30.00 was originally given to the hotel owner
* Correct price of the room = $25
* Each man receives $1 dollar refund = $3
* The owner receives a $2 tip
* $25 for room + $2 tip for the owner = $27
* $30 - $27 = $3 which is how much the men receive back as a refund.