Trigonometry (10th Edition)

1. Internal angles of a triangle have a sum of 180° (x+15)+(x+5)+(10x-20)= 180 2. Solve the equation for x x+10x+x=180-15-5+20 12x=180 x=15$^{\circ}$ 3. Then find angles by replacing x=50 (15)+15=30$^{\circ}$ (15)+5=20$^{\circ}$ 10(15)-20=130$^{\circ}$