You can figure out angle b by solving for angle a first. Since angle a and 117 degrees are on the same line, both angles equal to 180 degrees. Subtract 117 from 180 and you get 63 degrees. So that means you have two angles of the triangle, 81 degrees and 63 degrees. Since a triangle is equal to 180 degrees, add both 81 degrees and 63 degrees then subtract the sum by 180. This would give you the answer of 36 which is angle b.
