Question 1122530
MP bisects LMN.


this forms LMP = PMN with LMP + PMN = LMN.


MQ bisects LMP.


this forms LMQ = QMP with LMQ + QMP = LMP


MR bisects QMP.


this forms QMR = RMP with QMR + RMP = QMP


RMP = 21.


QMR = RMP with QMR + RMP = QMP results in 21 + 21 = 42.


this means QMP = 42.


LMQ = QMP with LMQ + QMP = LMP results in 42 + 42 = 84.


this means LMP = 84.


LMP = PMN with LMP + PMN = LMN results in 84 + 84 = 168.


this means LMN = 168.


that's your solution as far as i can see.