Hi, here is the problem: Imagine three spherical masses all fixed on the x-axis: mass 5M at the origin, mass 2M at x =+12.0 units, and mass M at x = -8.0 units, all connected by a rigid rod whose mass can be ignored. At what position along the x-axis is the center of mass of the system located? is this the correct equation? if so, i don't know where to plug in the numbers. x = (m1x1 + m2x2)/ m1+m2 Thanks!!