Calculate k the change in the total kinetic energy of the

Question

On a frictionless horizontal air table, puck A (with mass 0.248 kg) is moving toward puck B (with mass 0.368 kg), which is initially at rest. After the collision, puck A has velocity 0.116 m/s to the left, and puck B has velocity 0.646 m/s to the right.

1. What was the speed vAi of puck A before the collision?
2. Calculate ΔK, the change in the total kinetic energy of the system that occurs during the collision.