Answer:
53 minutes
Explanation:
Let x minutes taken 20 people to paint 20 walls
53 minutes are taken for 6 people to paint 6 walls
Time taken by 1 person=

Time taken by one person = 53 minutes
Similarly, when 20 people have to paint 20 walls
It will also take 53 minutes.
Hence, the correct answer is 53 minutes.