Answer :
4 people paint 8 walls in 60 minutes
So 1 person paints 8 walls in 240 minutes
So 1 person paints 1 wall in 30 minutes
So 5 people paint 1 wall in 6 minutes
So 5 people paint 4 walls in 24 minutes
So 1 person paints 8 walls in 240 minutes
So 1 person paints 1 wall in 30 minutes
So 5 people paint 1 wall in 6 minutes
So 5 people paint 4 walls in 24 minutes