Anticlockwise moment = 40 gf × 40 cm

Clockwise moment = 80 gf × d cm

Clockwise moment = Anticlockwise moment

80 × d = 40 × 40

⇒ d = 40 × 40\over 80 = 20 cm

Therefore the bar will be in balanced position if weight of 80gf is placed at a point of 20cm to the right of O.