A mass is moving at in the +x direction and collides inelastically with a another mass of 4 kg moving at 7.1 m/s in the -x direction. After the collision, both masses are moving at 0.7 m/s in the +x direction and the total kinetic energy of both objects after the collision is 24 percent of total kinetic energy before the collision. What is the mass which was originally moving in the +x direction in kg?