Find the measure of the angle indicated by a "?

A full circle is equal to 360 degrees. The missing center piece, the arc length without an angle measurement next to it, would be the remaining angle measure that would make the full circle 360 degrees. B would be equal to half that arc angle.

Solving:

360 = B + 105 + 145

360 = B + 250

B = 110 / 2 = 55 degrees

Hope this helps!! :)

I am especially when your teacher doesn't explain to you what your doing but uses resources to help me since I'm online. I don't really get any of my work really but some how get a good grade?.

Step-by-step explanation: