OK, I'll be a bit serious... no, it's not easy for me

As others have said, this is a pretty famous problem, and you may well have already Googled the solution. The answer is that the numbers are added incorrectly.

But the numbers are fine. Consider: when all is said and done, the room is $25. They tipped the bellhop $2. $25 plus $2 is the $27 total paid, or $9 per man.

Suppose the bellhop had made a really big error and said the room is $16 per night, not $30. Okay, so he gives each man $4 back, and says I cannot make change for the $2 i have left. They let him keep it.

Using these numbers, the problem would have been worded something like:

"So each man paid $6. $6x3 is $18 plus the $2 the bellhop kept, which is $20. Where is the missing $10 to make $30?"

...and that question will likely be pondered far less. A much bigger error causes one to consider sooner that something is amiss.

The problem has stuck since the "difference" using this funny reasoning and the numbers it does is only $1. When it gets bigger than that, as it just did when we used different numbers, the faulty addition is easier to see...