There are two rubber ducks on the counter. If you take two of them, how many rubber ducks do you have?
Two, since you take two.
Isn't it 0? 2 ducks, take away two ducks. 0 ducks?
Uhh... if you take 2 and there are 2 on the counter.
You have 0 left?
The question is how many do YOU have, not how many are left. So two, since you took two.
Depends on how many you HAD before you stole 2 more from the counter !