so, the sum of a triangle's angles should be 180°. the 2 angles are 60°, and if you add them up, it's 120°. 180° - 120° = 60°. the angle LMN is 60°. if a triangle has all three equal angles, that means it's a equilateral triangle. an equilateral triangle is a triangle with all equal angles, and sides. side LN is 16, so the rest should be 16. so the x is 16.