Question

After sliding down a snow-covered hill on an inner tube, Ashley is coasting across a level snowfield at a constant velocity of +2.8 m/s. Miranda runs after her at a velocity of +4.8 m/s and hops on the inner tube. How fast do the two of them slide across the snow together on the inner tube? Ashley's mass is 69 kg and Miranda's is 61 kg. Ignore the mass of the inner tube and any friction between the inner tube and the snow.