Word Problems: Evaluation, Substitution

3 fellows go into a hotel. The desk clerk tells them that it will be $30 for the night, so each one pays $10 and they head off to the room for the night. Shortly after, the manager reminds the desk clerk that they are running a special that night, and it's only $25 for the room. The desk clerk pulls out five singles and gives them to the bell boy to return to the fellows. On the way up to the room, the bell boy realizes that it will be impossible to evenly split the $5, so he takes $2 for himself. Once he gets to the room, he explains to the fellows what happened, and returns the $3, one for each fellow. This means that each fellow paid $9 for the room.

Now, add it back up.

They each paid $9. 9 times 3 is 27. The bell boy took $2, that makes 29. Where is the extra dollar?

any explanations??? THANKS!