Patrick B. answered 01/31/21
Math and computer tutor/teacher
angle PMN = angle PNM given
angle CMP + angle PMN = 180 definition of supplementary for
angle DNP + angle PNM = 180 linear pairs
angle CMP + angle PMN = 180 transitive / substitution
angle DNP + angle PNM
angle CMP = angle DNP subtraction property of equality