Momentum where an object explodes into two peices

[h.bonnie94]

A 12 kg mass is initially moving due east at 6 m/s on a frictionless surface. It suddenly explodes into two pieces, both of which move along an east/west line. If one fragment of 8 km is moving at 18 m/s east after the collision, find the velocity of the other fragment.

 

[nil1996]

Welcome to forum.So how did you attempt the problem.