Answer:
37°
Explanation:
AngleBCD is called an exterior angle of the triangle. AngleA and AngleB are called remote interior angles (because they are away from the exterior angle)
Anyway, it works like this:
AngleA + AngleB = AngleBCD
A + B = BCD
We are given two of these values, so we can find the third one.
A + 86° = 123°
Subtract 86°
A = 123 - 86
A = 37
The measure of Angle BAC is 37°