What I did was I created a parallel line to lineXY at the top of the triangle (going through point C) and filled in angle values for alternate interior angles.
Then, I subtracted 80 and 40 from 180 to get 60, but I'm not sure if this is the correct answer.
Then, I subtracted 80 and 40 from 180 to get 60, but I'm not sure if this is the correct answer.