Newtons 3rd law and the combinations of the laws worksheet please help : :)

11. A physics student is waterskiing behind a power boat and pondering Newton's 3" law. List 2 different pairs of action-reaction forces in this situation. Action: Reaction: Action: Reaction: Combinations of the Laws 12. A boy on a skate board (combined mass 80 kg) throws a 2.0 kg textbook east with a force of 8.0 N. Find the acceleration of the textbook and the acceleration of the boy on the skateboard. 13. Find the net force and acceleration of the object shown: 12.0 N 5.0 N mass = 100 g 9.0 N 4.0 N 3.0 N