so 5 people work each one for 21 minutes, that means 21+21+21+21+21 minutes altogether, namely 105 minutes, it took that long for 7 walls, hmmmm how long for just one wall then? well, 105 ÷ 7, namely 15 minutes then, for just 1 wall.
now, if it takes 15 minutes of work to do one wall, what about 5 walls? well, that'd be 15*5 or 75 minutes.
so if we have 3 folks working, how much would each one work? well, 75 ÷ 3, namely 25 minutes, so each of them will work 25 minutes, namely 25+25+25 minutes, so in 25 minutes, they'll be done with 5 walls.
Answer:
Give me a second I know this one.
Step-by-step explanation:
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Answer:

In order to maximize the last equation we can derivate the function in term of x and we got:

And setting this derivate equal to 0 we got:

And solving for x we got:

And for this case the value that maximize the profit would be x =95 and the corresponding profit would be:

Step-by-step explanation:
For this case we have the following function for the profit:

And we can rewrite this expression like this:

In order to maximize the last equation we can derivate the function in term of x and we got:

And setting this derivate equal to 0 we got:

And solving for x we got:

And for this case the value that maximize the profit would be x =95 and the corresponding profit would be:

19 minutes I think just divide 323 and 17
They all have the same y-intercept