If the measure of an angle is 12 degrees less than the measure of its supplement what is the measure of the angle

Nina has prepared the following two-column proof below. she is given that ∠oln ≅ ∠lno and she is trying to prove that ol ≅ on. triangle oln, where angle oln is congruent to angle lno nina made two errors in the proof. identify and correct the errors.