Two bodies of masses 10 kg and 2 kg are moving with velocities $2m/s$ and $10m/s$, towards each other . The velocity of their centre of mass is

Question

$$\begin {array} {1 1} (a)\;\frac{10}{3}\;m/s & \quad (b)\;5\;m/s \\ (c)\;2\;m/s & \quad  (d)\;zero \end {array}$$