180°-75°- 40° =105°-40° =65°
180°-(75°+ 40°) =180°-105° =65°
65
180°-40°-60° =140°-60° =80°
180°-110°-55° =70°-55° =15°
180°-90°-55° =90°-55° =35°
90°-55° =35°
