In a football game, a receiver is standing still, having just caught a pass. Before he can move, a tackler, running at a velocity of +4.4 m/s, grabs him. The tackler holds onto the receiver, and the two move off together with a velocity of +2.9 m/s. The mass of the tackler is 120 kg. Assuming that momentum is conserved, find the mass of the receiver.
120*4.4 = (120+m)*2.9
now just solve for m