Answer:
B. BD = 9
Step-by-step explanation:
Simply set the 2 equations equal to each other (both are congruent due to perpendicular bisector):
6x + 3 = 3x = 6
3x + 3 = 6
3x = 3
x = 1
Then substitute 1 for x in BD
6(1) + 3
6 + 3
BD = 9
