Two gliders collide on an air track moving in from opposite directions, and they bounce back. The masses of the gliders are 0.20 kg and 0.30 kg. The magnitudes of their initial velocities are 0.50 m/s and 0.40 m/s, respectively. After the collision, the magnitudes of their velocities are 0.40 m/s and 0.20 m/s, respectively. Assume the first glider is initially heading in the positive direction. The total momentum of the gliders before collision is closest to: