The answer is in the way the question is worded. You cannot add what one person HAS to what someone else has PAID and come up with any kind of a meaningful number, you have to subtract.
Each man has paid $9. The bellhop has $2. Difference | $9 x 3 = $27 2 $25 |
To look at it from the standpoint of the original $30.
Each man has $1. The bellhop has $2. The hotel clerk has $25. Total | $1 x 3 = $3 2 25 $30 |