Physics Force & Laws Of Motion Level: Misc Level

Two wads of putty are propelled directly toward each other in the horizontal plane.Wad -1 has a mass of 5.00 kg and is traveling at 21.0 m /s south. Wad -2, which is 6.00 kg, is moving at 12.0 m /s north. They collide and stick together. What is the velocity of the joint mass of putty?