Explanation: Well, think about it if you see it on the logical end, there are 8 men that mean 16 legs. Then there are 4 legs of the couch as well that made it total of 20. If broken legs are of the men, then still the total will be 20 because the legs are still intact but 6 men left that means 12 legs are gone, if 3 legs break and 6 men leave. the number of legs remaining are 20–6*2–3=5.... so it's 5 I hope this helps! xoxo
If net external force acting on the system is zero, momentum is conserved. That means, initial and final momentum are same → total momentum of the system is zero.
