Making $25 out of the numbers you have is the easy part but doesn't explain the missing $1. $30 paid..... 5 dollars refunded.... Now, the total money paid is $25 Keep an eye on the $5 refund. We must account for it. $3 was refunded, right? and $2 was kept by the bellboy. So we can see the $5! This means each man paid $9 for the room..... Always account for the $5 refund. 9x3=27 with this we can see the $3 that was refunded to the men,right? now we add the $2 the bellboy kept. There is our $5, $3 refunded and $2 kept. But 27+2=29. Where's the other $1.