What is the speed of the third piece?

A spaceship of mass 1.9�106 kg is cruising at a speed of 5.4�106 m/s when the antimatter reactor fails, blowing the ship into three pieces. One section, having a mass of 5.0�105 kg, is blown straight backward with a speed of 2.4�106 m/s. A second piece, with mass 8.5�105 kg, continues forward at 8.0�105 m/s.