Final answer:
Bella must travel upwards a total of 3 floors from the garage to the lobby, and then an additional 9 floors from the lobby to her 9th floor office, making it 12 floors in total.
Step-by-step explanation:
If Bella's car is parked 3 floors below ground (the garage), and her office is on the 9th floor, we need to calculate the total number of floors she must travel to get from her car to her office.
Since the lobby is the zero point, we consider it as the baseline.
From the garage to the lobby, Bella travels 3 floors upward. From the lobby to her 9th floor office, she travels an additional 9 floors upward.
The total is 3 + 9, which equals 12 floors in total that Bella needs to travel upwards.