Three masses lie on the x-axis. Object A is at the origin and has a mass of 199.1 kg. Object B has a mass of 592.9 kg and is located 7.5 meters in the positive x direction from A. Finally, object C, which has a mass of 330 kg, is positioned 4 meters from object B, so that object B is between objects A and C. What is the force acting on object A? (The sign of your answer will denote direction.) The force on A is _?