An Easy One...
 

To get warmed up, or cold -- as they case may be. There is a difference between a riddle and "problem", which shall be explored subsequently. Winners may have to be ackmowledged in other threads.

Three friends check into a motel for the night and the clerk tells them the bill is $30, payable in advance. So, they each pay the clerk $10 and go to their room. A few minutes later, the clerk realizes he has made an error and overcharged the trio by $5. He asks the bellhop to return $5 to the 3 friends who had just checked in. The bellhop sees this as an opportunity to make $2 as he reasons that the three friends would have a tough time dividing $5 evenly among them; so he decides to tell them that the clerk made a mistake of only $3, giving a dollar back to each of the friends. He pockets the leftover $2 and goes home for the day! Now, each of the three friends gets a dollar back, thus they each paid $9 for the room which is a total of $27 for the night. We know the bellhop pocketed $2 and adding that to the $27, you get $29, not $30 which was originally spent. Where did the other dollar go????

They each spent 8 1/3 dollars which totals 25 dollars plus bellhop has 2 which equals 27 plus they each got one dollar back equalling 30 dollars. So what part dont you understand?