For a system of three particles moving along a line, an observer in a laboratory measures the

Question:

For a system of three particles moving along a line, an observer in a laboratory measures the following masses and velocities. What is the velocity of the cm of the system?
Mass (kg) vx (m/s)
3.0 .......................+290
5.0 .......................−120
2.0 .......................+52