When we bisect an angle, the angle is cut in half. This means that ∠ABD = ∠DBC = 1/2 ∠ABC
Now that that's settled, we can set up the equation:
3x + 36 = 1/2(7x)
Multiply both sides by 2:
2(3x + 36) = 7x
Distribute:
6x + 72 = 7x
Isolate the variable by subtracting 6x:
72 = x
Now that you know x, you can solve for ∠ABD. And because that's equal to ∠DBC, you'll be getting that answer, too.
Therefore, the answer is B. 72
Hope this helped! Let me know if you have any questions and mark me Brianliest please:)
