Answer:
C. 5
Explanation:
∆LMN kid an isosceles triangles because it has two base triangles that are equal to each other. Therefore, the sides opposite the base triangles would also be equal to each other.
Thus:
3x = x + 10
Solve for x. Subtract x from each side
3x - x = 10
2x = 10
Divide both sides by 2
x = 5