The Bellhop Problem: 27 + 2 = 30
Basic Algebra: Three guests rent a room for $30. They pay $10 each. The manager decides to instead charge $25 and sends the bellhop to return the $5 in change. The guests keep $1 each and pay $2 to the bellhop. Since each guest pays $9, the total payout is $27 + $2. What happens to the extra dollar.