To find the top angle inside the tringle, do 180-133 = 47. To find the angle on the left, do 180 - 142 = 38. Do 180 - 47 + 38 = 95 to find the final angle. Then do 180-95 = 85 to find the angle wanted. This is all about using lines, because the angles on both sides of the line must add to 180 if one of the lines they lie on is the same. Hope this makes sense.
