There is a triangle rule that states the outer angle of an angle in a triangle is equal to the sum of the remaining two angles in that triangle, which means that m∠2 = 52° + 68° = 120°. This can be proven correct because the sum of two of the angles in the triangle is 120°, which means the final angle is 60°. Since m∠2 is the outer angle of 60°, that means it will be 180° - 60° or 120°.
