Which regular polygon would have each of its interior angles measure 140°?
nonagon
heptagon
octagon
decagon

Nonagon

sum of the angles of a polygon is (n-2)*180
each angle is (n-2)*180/n
140 = (n-2)*180/n
140n = 180n - 360
-40n = -360
n = 9

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.