In the diagram, QOR + 2m(vertically opposite angles)So, m + 90° + 2m = 180°(angles on str. line)3m = 180° - 90°3m = 90°m = 90o3= 30°substituting 30° for m in2m + 4n = 200° gives2 x 30° + 4n = 200°60° + 4n = 200°4n = 200° - 60°= 140°n = 140°4= 35°