Answer:
The answer to your question is 14 floor
Step-by-step explanation:
To solve this problem start from the end changing the sense if it says up, then consider the action as down, etc.
Last floor = 12
Go down 4 floors = 12 - 4 = 8
Go up 8 floors = 8 + 8 = 16
Go down 2 floors = 16 - 2 = 14
Conclusion
At the beginning I was on the 14 floor