Answer:
MN = 68
Explanation:
LN = 91
LM = 23
Points L, M, and N are collinear, therefore, according to the segment addition postulate, the following can be deduced:
LM + MN = LN
23 + MN = 91 (Substitution)
Subtract 23 from both sides
23 + MN - 23 = 91 - 23
MN = 68