Answer:
Option в. 42°
Step-by-step explanation:
The picture of the question in the attached figure
we know that
If the ray BD is the ange bisector of angle ABC
then
ray BD divide angle ABC into two equal parts
so
[tex]m\angle ABD=m\angle DBC[/tex]
[tex]m\angle ABD=\frac{1}{2} m\angle ABC[/tex]
substitute the given value
[tex]m\angle ABD=\frac{1}{2} (84^o)=42^o[/tex]
