So Three guys get together and decide to take an extreme hiking tour on a budget and found a $30 hut they could all pitch in to stay in near such a place. 

When they arrived in high spirits, their check-in left an impression on the clerk. He was so moved by their excitement and passion that he decided to provide them with a discount to which amounted $5 

He gives this 5 dollars to his helper and asks him to return it to the gentlemen that just checked in. 

On the way, this helper had decided that $5 is too hard to split evenly between the 3 guys, so he gives them $1 each and keeps $2 for himself.

We know that each guy paid $9 each so we have $27 and the helper kept $2. $27+$2=$29 

WHAT HAPPENED TO $1 DOLLAR!?!?