If you're going to do a multiple choice question, please include the choices so we can better help you!
I think 1 because if you had 2 you'll end up with a shape that is greater than 180 degrees. Keep in mind obtuse angles a over 90 degrees. hope that helped
The slope is 0 the equation of the line is y=3
X - y + x + y = 180
2x = 180
x = 90
2x - 2y = x + y
x = 3y
y = x/3
y = 90/3
y = 30
x - y = 90 - 30 = 60
x + y = 90 + 30 = 120
2x - 2y = 180 - 60 = 120
