Answer:
It takes 46 minutes for 10 people to paint 3 walls
It takes 92 minutes for 10 people to paint 6 walls (twice as long because you have twice as many walls)
You only have 4 people to paint the walls instead of 10 people
Therefore it will take 2.5 times as long (10/4=2.5)
2.5*92=230 minutes
