Question 53294
Supplementary angles are angles that add together to = 180 degrees (a straight line)
If two angles + together=180
The smaller angle=x
The larger angle is 20 degrees less than (-20) three times (*3) the smaller angle (x).  The larger angle=3x-20.
Your problem to solve is:
Smaller angle + larger angle=180
(x)+(3x-20)=180
(1+3)x-20=180
4x-20=180
4x-20+20=180+20
4x=200
4x/4=200/4
x=50
The smaller angle:x=50 degrees
The larger angle:3x-20=3(50)-20=150-20=130 degrees