In the figure, OA and OB are opposite rays.
(i) If ∠ BOC= 75°, find ∠ AOC
(ii) If ∠ AOC= 110°, find ∠ BOC.
                       

(i) OA and OB are opposite rays, then ∠ AOC and ∠ BOC form a linear pair.
∴ ∠ AOC + ∠ BOC = 180°
If ∠ BOC = 75°, then
   ∠ AOC = 180° -75°
             = 105°
(ii) If ∠ AOC = 110°, then
      ∠ BOC = 180° - 110°
                = 70°