Two hockey players skating on essentially frictionless ice collide head-on. Madeleine, of mass 65.0 kg, is moving at 6.00 m/s to the east just before the collision and at 3.00 m/s to the west just after the collision. Buffy, of mass 55.0 kg, is moving at 3.50 m/s to the east just after the collision. Find Buffy's velocity (magnitude and direction) just before the collision. Express your answer with the appropriate units. Enter positive value if Buffy is moving to the east and negative value if Buffy is moving to the west. H 0 ?