Пусть ∠AOC = x, тогда ∠BOC = x + 18°.
∠AOC + ∠BOC = ∠AOB → x + (x + 18°) = 70° → 2x + 18° = 70° → 2x = 52° → x = 26°.
∠AOC = 26°, ∠BOC = 26° + 18° = 44°.