How to calculate distance object traveled in completely inelastic collision?

[pebbles]

Ok, so I have this practice problem: a mass of 5 kg has hit a ball at 8 m/s. The ball it hit has a mass of 7 kg. What is the distance the ball traveled?


It's really frustrating when my notes don't go over ANY of this.

 

[Galileo]

Are you sure that's the entire problem statement? It doesn't make much sense as it is.
Distance traveled as in: how far from the moment of impact till it hits the ground? That would depend on the height at which the collision took place.