They are friends of Mary. They are Mary's friend. The apples of this tree are red. Correct. No change. 13) What's the price of this clock? 14) The testof James was bad. 15) Thebackpacks of the children are cute 16) It is the birthday of my mother 17) The ingredients of the pizza are spicy. 18) The bike of Paul is white. 19) The kite of my brothers is yellow 20) The paper of the bag is strong