They started with $30. The salesmen paid $27 ($9 x 3) and the bell hop kept $2. $27 plus $2 is $29. What happened to the extra $1?

There's $30 to start with, the motel takes $25, the salesmen take $3, the Bellhop takes $2. That's $30!

The error occurs when some of the parts are paying money and some are taking money, which is mixed math.

Hey that was fun. Right I haven't heard that problem since the 60s.