Center Of Mass

A \(1 \mathrm{~kg}\) ball moving at \(12 \mathrm{~ms}^{-1}\) collides with a \(2 \mathrm{~kg}\) ball moving in opposite direction at \(24 \mathrm{~ms}^{-1}\). If the coefficient of restitution is \(2 / 3\), then their velocities after the collision are