how to solve this

how to solve this A panicle of mass 10 kg. which initially was at rest. staits sliding down a smooth inclined plane at an angle 30 degrees to the horizontal. After 4 seconds. the panicle explodes into two particles of equal mass. One of the panicles moved in a horizontal direction with velocity mgs. while the other continued to mcve along the inclinad plane with velocity 16 m/s. How long the explosion had occurred? A) 8) D) 1.6 seconds 0.75 seconds 1.26 seconds 0.8 seconds