bantu pliss.. tulis caranya yaa....

∠CBA = 180° - 140°
           = 40°
180° = ∠CBA+∠BAC+∠ACB
        = 40°+(y+10)°+(2y+10°)
180° = 60°+3y
3y = 180°-60°
     = 120°
y = 120°÷3
   =40°
∠BAC = y+10°
           = 40°+10°
           = 50° (C)

semoga bermanfaat yaa