Step-by-step explanation:
hope this helps you dear friend.
The pree tax amount count as 100%, then there's the 7% tax and lastly the 20% tip. therefore, one would pay (100+20+7)% of $84.00.
127% of $84.00
(127/100) * $84.00 = $106.68
I got ECHA... hope it's right:)