A spaceship of mass 2.10×106 kg is cruising at a speed of 4.00×106 m/s when the antimatter reactor fails, blowing the ship into three pieces. One section, having a mass of 4.80×105 kg, is blown straight backward with a speed of 1.80×106 m/s. A second piece, with mass 8.10×105 kg, continues forward at 1.30×106 m/s. What is the speed of the third piece?