wh00t's explanation, while entirely correct, didn't point out the

logical fallacy quite clearly enough for a friend of mine (

who shall remain nameless, Ian), so here it goes, for the slow ones:

The original premise:

The businessmen payed $9 a piece, for a total of $27, plus the bellhop's $2 makes $29, so where's the extra dollar?

The corrected premise:

The businessmen payed $9 a piece, for a total of $27, *minus* the bellhop's $2 makes $25, the price of the room.

Hope that clears up any remaining confusion.