DAY 1
You start with 4
You triple it to get 12
You subtract 2 to get 10
DAY 2
You start with 10
You triple it to get 20
You subtract 2 to get 18
DAY 3
You start with 18
You triple it to get 54
You subtract 2 to get 52...
This isn't going anywhere, now is it? You're never going to reach zero, it must be a trick question.