I believe the answer is 21. I can tell you how I got the answer if you want.
Mia gives $80 as tip to the movers.
<em><u>Explanation</u></em>
The moving company charged $500 for its service.
Suppose, the amount of tip is
dollar, which is 16% of the total charge.
So, the equation will be.....

So, the amount of tip Mia gives the movers is $80