The trick for the ultimate question is that the number "$29" is a complete fabrication: They paid $25, plus $2 stolen by the bellboy, so $27 in total. They retained $1 each, so $27 + $3 = $30. By saying "they each got back $1 plus the bellboy had $2", they are tricking you into counting the bellboy's $2 twice.
thanks! I didn't noticed this bug; I'll fix it!