The answer to the math problem is simple when defined with pure logic. You have used deliberate misdirection in your wording of the problem. The $2 the bellboy kept was in fact a refund, not a charge, therefore you shold subtract it from the total, not add it.
$10 + $10 +$10 = $30
$30 - $1 - $1 - $1 = $27
$27 - $2 = $25, the correct price for the room
The bellboy gave each man two dollars back making the price of the room $27. The extra $2 was kept by himself giving us the correct total of $25
Welcome rage ^^ Good to have you on board