Short answer B
The insert just confuses the issue. The total number of floors traveled is 34. Let's see which answer gives that.
A
| 9 - 12 + 5 - 8|
| - 3 - 3 |
| - 6 |
6 That's not 34, so it's not the answer.
C
9 - 12 + 5 - 8
-3 - 3
- 6
That's not 34 so C is not the answer.
D
Same answer as A and done the same way. Just remove the brackets.
|9 - 12 + 5 - 8 |
| - 3 - 3 |
6
Must be B. <<<<< answer
9 + 12 + 5 + 8
34