This isn't really homework, but something for you to think about...
Three men went to a hotel and rented a room for the night. it was $30 for the room for one night. So each man payed $10, totalling the $30.
Later that evening, the receptionist realized that he had over charged them, and that the room was only $25. He gave $5 to the bellboy to give the men.
The bellboy didn't know how he would give the three men equal amounts, so he gave them $3 and kept the $2 for himself.
This meant that the three men payed $9 each (3x9=27) and the bellboy has $2, (27+2=29) only totalling $29. Where's the other dollar?