а) ∠NOK = 180° - 123° = 57°
б) 360° = х+2х+4х+5х = 12х
х = 360°/12 = 30
∠1 = 1*30 = 30°
∠2 = 2*30 = 60°
∠3 = 4*30 = 120°
∠4 = 5*30 = 150°
