One ball of mass 0.500 kg traveling 6.00 m/s to the right collides with a ball of

Question:

One ball of mass 0.500 kg traveling 6.00 m/s to the right collides with a ball of mass 0.200 kg initially at rest. After the collision, the heavier ball is traveling 2.57 m/s to the right. What is the velocity of the lighter ball after the collision?