Please submit your concern

Explanation:

In this triangle, AD = DC = BD = $\frac{105}{2}$ = 52.5 km.
(Note: The best way to solve this question is to treat questions 104 and 105 together. You would figure out that the answer to question 105 has to be half of the answer to question 104, and the only pairs of answer choices that fit into this condition are 105 and 52.5)