Final answer:
The question does not give enough context or data to determine the total cost of the building and the additional floor constructed. Additional information is needed to provide an accurate answer.
Step-by-step explanation:
The question provided does not include enough information to accurately determine the total cost of the office building purchased by Tristen Company and the cost of the construction of an additional floor. To correctly calculate the total cost, we would need the individual costs of the building and the sixth-floor construction. The possible answers provided a), b), c), d) are lacking context, and as such, without additional data or context about the original cost of the building and the construction costs of the additional floor, it is not possible to give an exact answer.