Where is the lost dollar?

Question

Somebody explained me this problem, but I am not sure to understand what is wrong.

Three people go to a bar to have a drink.
To pay the bill everyone gives $10.
The barman gives back $5 coins.
Every people take $1 back and leave the $2 other dollar for the barman.

If everybody give \$10 and get \$1 back, they paid \$9 right?

3 * $9 + $2 = $29

Where is the missing dollar?

Answer 1

True $3*9=27$.

But they paid $25\$$ and gave $2 \$ $ tip. And

$$25+2=27=3*9 \,.$$

Answer 2

There is no missing dollar.

\$30 - \$5 = \$25 paid to the barman. \$2 tip + $3*\$1$ = remaining \$5.

Answer 3

The math is simples:

1. 10*3 = 30 and 30-25 = 5
2. (1*3)+2= 5

∴

There is no loss.