Answer:
18 days.
Explanation:
We have been given that 12 painters paint the wall of a school in 21 days.
So the wall painted by one painter will paint the wall in
As one painter will paint the wall in 252 days, so to find the number of days it will take to paint the same wall by 14 painters, we will divide time taken by one painter (252) by 14.
Therefore, it will take 18 days to paint the same wall by 14 painters.