Center of Mass Problem with an initial center of mass?

2017-11-11 14:38:47

The problem begins by stating the CM of an empty 1300kg platform is 2m from the front of the platform.

The problem gives a mass of 120kg that is 2.35m from the front of the platform and a mass of 180kg that is 3.45m from the front of the platform.

When asked to find the new center of mass,xCM = (120kg * 2.35m) + (180kg * 3.45m) / (300kg). I obtained 3.01m for my answer.

However, I did not use the given CM of the empty platform, and the 1300kg that is the weight of the platform. How do I factor the beginning information into my formula?