physic question.?

Question

A 30 gr ball with 10 m/s velocity hit to another ball that is motionless. Then the ball with 6 m/s velocity scatter. If the mass of the motionless ball be 100 gr , how much is the velocity after hitting?

Answer 1

momentum before 300=momentum after=30*6 +100*x. Therefor x =1.2 m/s