Answer:
Explanation:
Notice that the measure of angle 5 is congruent, or equal to, the measure of angle 1. You entered this in one of your previous steps. Since the measure of Angle 1 is CONGRUENT to the measure of Angle 5, you can substitute Angle 5 for Angle 1.
Similarly, the measure of Angle 3 is congruent to Angle 6. So you can write that the m(Angle 5) + m(Angle 2) + m(Angle 6) = 180. By method of substitution.
I'm not exactly sure if this is the right order they want you to do it, however I hope this helps.