A robotic rover of mass 12 kg travelling at 3.5 m/s to the east on a flat Martian surface collides head-on with a stationary science package of mass 15 kg. Immediately after the collision, the rover rebounds to the west at 0.5 m/s.
What is the velocity of the science package immediately after the collision?
2.4 m/s2.4\text{ m/s}2.4 m/s to the east
2.8 m/s2.8\text{ m/s}2.8 m/s to the east
3.2 m/s3.2\text{ m/s}3.2 m/s to the west
3.2 m/s3.2\text{ m/s}3.2 m/s to the east