Collision problem help needed

Hi I wonder if anyone can help, im stuck on this question.

1.Two smooth spheres A and B, of masses of 300g and 700g respectively, are travelling towards each other along the same horizontal line with speeds of 8m/s and 4m/s respectively. After the collision, the direction of motion B has been reversed and its travelling at a speed of 2m/s

Find:
a)The final speed of A after the collision
bThe total loss in kinetic energy due to the collision.


Any help would be greatly appreciated.