"Three people go to the restaurant to pay $10 each, but because the restaurant to do specials can be returned $5, but the waiter greed private deduction of $ 2, the remaining $ 3, so they paid 27 plus deducted $ 2, only $ 29, then the remaining $ 1 where to go?"

In fact, the correct way to think about it is like this:

"Three people go to a restaurant and pay $10 each, but because the restaurant is running a special it can return $5, but the waiter is greedy and deducts $2 privately, leaving $3, so what they pay is 27 plus the returned $3, which is $30."

Confused thinking leads to this.