Answer:
20 minutes.
Step-by-step explanation:
Since it takes 5 people to paint 5 walls 20 minutes, that means that it would take 1 person 20 minutes to paint 1 wall. That also means that 2 people would take 20 minutes to paint 2 walls. So, it would take 9 people 20 minutes to paint 9 walls.
Hope this helps!
