Let one supplement angle=x
Twice of supplement angle=2x
so we know two supplement angle =180°
Then
x+2x=180°
3x=180°
x=180÷3=60°
2×60=120°
Or Simply
Supplement = 180 - angle measure. Supplementary angles add to 180 degrees.
So of the measure of the angle is x, the measure of its supplement is 2x.
x + 2x = 180
3x = 180
x = 60
Angle = 60, supplement = 120