Answer:
84 minutes.
Explanation:
In order to solve this, we jut have to calculate how many minutes does it take a person to paint a wall, so we multiply 60 minutes, by the number of people that worked on it, 7, so it takes 420 minutes of human work to paint 5 walls, how many minutes of human work would it take to paint one?, we just have to divide 420 by the number of walls, we know that the answer is 84, so if we have 10 walls to paint, and 10 people available to paint them, it would take them 84 minutes, sinces each person would paint a single wall.