A couple of M2 questions

A spaceship of mass 50000kg is travelling through space with speed 5000m/s when a crew member throws a box of mass 5kg out of the back with speed 10m/s relative to the spaceship.

i) What is the absolute speed of the box?
ii) What is the speed of the spacehip after the box has been thrown out.

don't really know how to get started on this one

Two people, masses 70kg and 50kg are standing facing each other on smooth ice. They push each other with force 35N for 1.5 seconds.

i) done

ii) What is the velocity of each of them after they push?

likewise, i'm not really sure exactly where to start

Help will be greeted with mucho thanks. :wink: