Answer:
C
Step-by-step explanation:
Since BD and DC are congruent, we know that DA bisects <BAC.
This means that <BAD and <CAD are congruent.
We can set up an equation for that.
3x+7=10x-7
Subtract 3x from both sides.
3x-3x+7=10x-3x-7
7=7x-7
Add 7 to both sides.
7+7=7x-7+7
14=7x
Divide both sides by 7.
x=2
Plug that back into expression for m<CAD.
10x-7
10(2)-7
20-7
13 degrees.
