The correct answer is it is a figure with at least 3 straight sides. When you think of a square or a triangle they both have at least 3 sides that are straight. A circle doesn't have any straight sides so it is not a polygon.
You can prove that the other answer is wrong because of two things:
The definition of a polygon is a plane figure with at least three straight sides.
Also, when you think of most shapes what do they all have in common? The have at least three straight sides
He has 2/3 left to complete.
He did 5 out of 15 which is 5/15 or 1/3. Therefore he has 1-1/3 or 2/3 left.
y = 7 + 3x
y = 3x + 7
y = mx + b, therefore the y-intercept is 7.
3y = 6x + 12
y = 2x + 4
y = mx + b, therefore the y-intercept is 4.
