Answer
Option B is correct.
x = 110°
Step-by-step explanation
The key to solving this is shown in this image attached below
From the image, we can apply this to the question and see that
½ (210° - x) = 50°
Multiply both sides by 2
210° - x = 100°
x = 210° - 100°
x = 110°
Hope this Helps!!!