Answer:
The first diagram is balanced, however the other two are unbalanced. The first is balanced due to the fact that each side is receiving 20N of force from the dogs pulling on the rope and so the rope will not be very likely to move. The second rope shows a 20N and 12N dog which is unbalanced due to the fact that the 20N dog is pulling with more force and is likely to drag the small dog towards it showing an unbalance as the rope moves. The third rope shows 3 different forces, in a sense, which are the small dog, big dog, and the pole. The small dog pulls with 12N, big dog with 20N, and pile with unknown, however it is unbalanced as despite the rope being there to likely balance the pull the big dog will still pull stronger and is likely to get more rope on their side showing an unbalance.