Since the distance of MN is 31 and we have a distance of ML of h -15 and LN of 2h – 8, therefore
ML + LN = h -15 + 2h – 8 = 31
h = 18
substituting the value of h to the expression for LN obtaining
LN = 2h – 8
LN = 2(18) – 8
LN = 28
Therefore the length of the segment LN is 28 units