Question

If 5 people can paint a house in 4 hrs, how long will it take 3 people??

As per book answer is 6 hrs 40 mints
But how????

Answer 1

So it would take 20 man-hours to paint the house, (or "person-hours to be politically correct)

No distribute those 20 hours needed among 3 painters, so it would take
20/3 hours
= 6 2/3 hours
= 6 hours and 40 minutes