Answer:
Lm = 30
Step-by-step explanation:
QP/LM = PN/NL
(x - 1)/(x + 3) = 12/18
18(x - 1) = 12(x + 3)
18x - 18 = 12x + 36
18x - 12x = 36 + 18
2x = 54
x = 54 : 2
x = 27
LM = x + 3 = 27 + 3 = 30