alternate interior angles means the angles across from another are equal. If you follow the line up 85 is directly across from 2x+1 then you can say 85 = 2x +1 85 -1 = 2x 84 = 2x 84/2 = x 42 = x
supplementary angles make a straight line so they must add to equal 180 degrees. That means the other angle 3y+5 = 180-85 3y +5 = 95 3y = 95-5 3y = 90 y = 90/3 y = 30
