The answer for the "Three Men Rent a Hotel Room" riddle is that the men are originally overcharged for the room at $30. Finally, they pay $25 for the room, give $2 to the owner as a tip and receive $1 each as a refund.
Each man initially pays $10 to rent the room, which equals a total of $30. When the owner informs them that the cost of the room is only $25, the men ask for the overpaid amount to be split up by giving each man back $1 with the owner keeping a $2 tip. All the money is accounted for, but the organization of the riddle makes it seem like money has gone missing.