Answer:
105°
Explanation:
The Arc DB = 150°,
If an angle goes from the center of the circle it is the same as the arc. If the angle is inscribed in the circle it is half the arc.
In this case A is inscribed in the circle so its value is half the arc,
The arc is 360 - 150 = 210°
Angle A = 210 / 2 = 105°