If two painters can complete two rooms in two hours, how many painters would it take to do 18 rooms in 6 hours?

Question

Pipe A can fill a cistern in 4 hours while pipe B can empty it in 6 hours. If both of them are opened together at the same time when the tank is empty, then how many hours would be taken by them to fill it?

Answer 1

2 painter takes 2 hours to Paint 2 rooms means,
1 painter takes 2 hours to paint 1 room.
So in 6 hours 1 painter can paint 3 rooms.
So to paint 18 rooms in 6 hours 6 painters are needed.

Answer is 6 Painters take 6 hours to paint 18 rooms