A 25 kg bumper car moving to the right at 5 m/s overtakes and collides elastically with a 35 kg bumper car moving to the right. After the collision, the 25 kg bumper car slows to 1.5 m/s to the right, and the 35 kg car moves at 4.5 m/s to the right. Find the magnitude of the velocity of the 35 kg bumper car BEFORE the collision. (type the NUMBER ONLY, do not include units or direction, round to 1 decimal place, do not use scientific notation)