What Determines the Velocity and Mass of the Second Ball in a Collision?

[RIO0311]

Homework Statement

A 0.220 kg ball traveling east at 8.5 m/s collide with a stationary ball. After the collision the first ball bounce back west at 3.7 m/s. What is the velocity and mass of the second ball?

Homework Equations

The Attempt at a Solution

 

[gneill]

Which conservation law do you think might e applicable?