Answer: B, x=20; angle measure is 30°.
Step-by-step explanation:
Opposite angles are always the same.
You can see that 30° and 3x are opposite angles therefore 3x=30°.
In algebra, when a letter and a number are next to each other, it means times.
So, 3x=30° means 3 times something equals 30.
And we know that 3×10=30 so, x=10.
Hope this helps :)
