Respuesta :

recall all interior angles in a triangle add up to 180°, therefore

[tex]\bf \stackrel{A}{x+40}~~+~~\stackrel{B}{2x-5}~~+~~\stackrel{C}{3x-17}~~=~~180 \\\\\\ 6x+18=180\implies 6x=162\implies x=\cfrac{162}{6}[/tex]