Two girls standing 20 m apart are both throwing balls towards a tree to knock down a shoe hanging 7 m up in a tree that is directly between them. Girl A is 7 m from the tree while Girl B is 13 m from the tree. They aim straight for the shoe. Neglect Gravity for this question. Girl A throws a ball with speed v while Girl B throws a ball with speed 2v. The ball thrown by Girl A lands the ground 3 seconds after it leaves her hand. By what vertical distance do the two stones miss each other.