A 0.020-kg bullet traveling at 200.0 m/s east hits a motionless 2.0-kg block and bounces off it,

Question:

A 0.020-kg bullet traveling at 200.0 m/s east hits a motionless 2.0-kg block and bounces off it, retracing its original path with a velocity of 100.0 m/s west. What is the final velocity of the block? Assume the block rests on a perfectly frictionless horizontal surface.