A ball of mass 0.220 kg that is moving with a speed of 7.5 m/s collides head on and elastically with

A ball of mass 0.220 kg that is moving with
a speed of 7.5 m/s collides head on and elastically with another ball initially
at rest. Immediately after the collision, the incoming ball bounces backward
with a speed of 3.8 m/s. Calculate (a) the velocity of the target ball after
the collision, and (b) the mass of the target ball.