Three friends decide to split the cost of a hotel room equally. They pay $10 each, totaling $30. Later, the hotel owner realizes that the room rate was only $25, so he gives $5 back to the bellboy to return to the friends. The bellboy, being dishonest, pockets $2 and gives back only $3 to the friends. Now, each friend has paid $9, totaling $27, and the bellboy has $2. But $27 + $2 = $29, so where is the missing $1?