3 girls go to a motel. The front desk clerk tells them the room will cost $30 for the night. Each girl gives $10 to make out the 30.
Later that night, the clerk realized that the room was actually $25, not 30. So, he calls one of his co-worker and give him $5 to return to the girls.
On his way, the co-worker ask himself:" How am I going to share $5 to 3 girls?" So, he decides to give each $1 and keep the extra $2 for himself.
So, each girl actually paid $9 for the room ($10-$1). So, the total should be $9+$9+$9 = $27. If we add the $2 that the co-worker kept, we get $29.
The question is: "WHERE IS THE MISSING DOLLAR??"