For brainleist answer and 30 points in advanced you are too kind : )

It is Figures A,B, and C. Answer D is not a polygon.

So for the first question, they are all polygons except for figure D, because a polygon is a figure with at least three closed lines and angles. 

The second question's picture seems to be a bit cut off, if you would tell me what the other angle measure is, I could definitely help you

The third question the answer would be A, since a regular polygon is one whose angles are the same size. 

-2x + 7 = 7

subtract 7 from both sides.

-2x = 0

divide both sides by -2.

x = 0

the value of x is equal to 0.