besar sudut AOB = 115 derajat.Nilai x =.... a.60 b.65 c.72 d.85

∠AOB + ∠BOC = 180°
115° + x° - 20° = 180°
x° + 95° = 180°
x° = 180° - 95°
x = 85 (D)

Dik :
∠ AOB = 115°
∠ BOC = (x-20)°

∠ AOB + ∠ BOC = 180°
115 + x - 20 = 180
x = 180 + 20 - 115
x = 85°