<span>m?ABC = 60°
Looking at the diagram, you have triangle ABC. For m?BAC you are given a value of 75°, m?ACB is a supplementary angle to 135° which means it has a value of 180° - 135° = 45°.
Finally, ?ABC is the 3rd angle of triangle ABC. Since all the angles in a triangle add up to 180°, you simply need to do the subtraction.
180° - 75° - 45° = 60°
Therefore m?ABC = 60°</span>
