X Y
————-
-2. -4
-1. -8
0. -12
1. -16
2. -20
To answer this item, we let x be the measure of angle Y. If we say supplement, it is understood that when we sum up the measures of the two angles (angle Y and its supplement) the answer should be 180. Therefore the other angle is 180-x. Going back to the condition given in this item, we will be able to generate an equation,
x = 3(180 - x)
The value of x from the equation is 135. Thus, m∠Y is 135°.
