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 +4.5 m/s, grabs him. The tackler holds on to the receiver, and the two move of together with a velocity of +2.6 m/s. The mass of the tackler is 115 kg. Assuming that the momentum is conserved, find the mass of the receiver.