Question 1158206
There is a double-counting of the $2.00 that the clerk pocketed.  So, it's not that $1.00 is missing; it's that $2.00 is double-counted.
<pr>
The total amount paid by the men is $27.00.  They paid $25.00 to the hotel and $2.00 to the clerk.  The way the problem is presented is that it says they paid $27.00, but then it also says the clerk received $2.00.  They are double-counting the $2.00.
<pr>
Total paid by the men = $27.00 ($25.00 to the hotel; $2.00 to the clerk).
<pr>
But, then the $2.00 is accounted for AGAIN (double-counted) when the problem mentions that $2.00 was taken by the clerk.
<pr>
The $27.00 paid by the men INCLUDES the $2.00 paid (stolen) from the clerk.  $27.00 is the real amount in play.  (Not $30.00, and certainly not $29.00.) 
But then, the problem mentions the $2.00 taken by the clerk, and tacks it onto the $27.00 to make $29.00. (The problem is, this $2.00 was ALREADY INCLUDED in the $27.00.)