If the larger angle is x and the smaller angle is y, y=(1/2)x+30 since it's 30 more than 1/2 of it. In addition, x+y=180 since they are supplementary. Plugging y=(1/2)x+30 into that, we get x+x/2+30=180=1.5x+30. Subtracting 30 from both sides, we get 1.5x=150. Next, we can divide both sides by 1.5 to get x=100 and y=(1/2)*100+30=50+30=80
