MHB How many minutes does it take 14 people to paint 14 walls

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It takes 28 minutes for 7 people to paint 7 walls, which implies that 1 person takes 28 minutes to paint 1 wall. Therefore, if there are 14 people painting 14 walls, they can work simultaneously on separate walls. Since each group of 7 people takes 28 minutes to complete their task, both groups will finish in the same time frame. Consequently, it will also take 28 minutes for 14 people to paint 14 walls.
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I need help with a question that has been bugging me for a while

Here is the question

It takes 28 minutes for 7 people to paint 7 walls.
How many minutes does it take 14 people to paint 14 walls?
 
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It takes 28 minutes for 7 people to paint 7 walls.

this statement is equivalent to saying it takes 28 minutes for 1 person to paint 1 wall ... so, how long for 14 people to paint 14 walls?
 
Imagine that as two separate work sites. At one 7 people are painting 7 walls. How long does that take them? At the other another 7 people are painting another 7 walls. How long does that take them? And, of course, the two groups of people started at the same time.
 
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