i'm willing to beat everyone at #10
so, A=72 degrees
divide 72 by 360 degrees, which equals:
0.20571428571
move decimal to the RIGHT (not left,titanium rome), and that would be 20.571428571%
so, overall, the answer would be A is 20% of the entire circle
p.s. to me the picture looks to me more like discongruent pizza slices
better get the larger one:E