Since all angles of a triangle add up to 180° we know x + 7x + x+9=180. then we combine like terms to get 9x+9=180. Next, we do inverse operation to find X. First subtract 9 from both sides of the equation to get 9x=171 then divide 9 from both sides to get x=19. No that we know x, we can find the values of the angles by putting in 19 for x. Bottom left angle is 19°, bottom right angle is 28°, top angle is 133°.
