Answer:
A
Step-by-step explanation:
The base angles L and N are congruent.
Thus the triangle is isosceles and ML = MN, that is
3x = x + 8 ( subtract x from both sides )
2x = 8 ( divide both sides by 2 )
x = 4
Thus
MN = x + 8 = 4 + 8 = 12 → A
