Question 1079215
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Answer: <font color=red>7 extra workers</font>


Explanation


There are many great solutions by the other tutors. 
I'll offer a different viewpoint.


Consider a job of moving 9000 boxes. 
I'm selecting this number since it's a multiple of 5 and 6, and because it's some large value.
It turns out that this value 9000 doesn't matter and you can pick any other value to get the same final answer at the end. 


If we had 5 men working to move 9000 boxes, then each man moves 9000/5 = 1800 boxes.
Each person has a daily unit rate of 1800/x boxes per day where x is the number of days to finish the job with 5 men.
Note that: rate = (amount done)/time


Adding a 6th man will mean each person handles 9000/6 = 1500 boxes.
Each person has a unit rate of 1500/(x-8) since they complete the job 8 days early. 


Assuming each man has the same unit rate, we can equate those fractions.
Solve 1800/x = 1500/(x-8) to get x = 48. I'll let the student handle the scratch work.
It will take x = 48 days if you had 5 men on the job.
The instructions state we want to finish 28 days earlier, so the timeline should be x-28 = 48-28 = 20 days.
Each worker's unit rate is 1800/x = 1800/48 = 37.5 boxes per day.


n = number of additional workers to hire in addition to the original 5 men
n+5 = number of workers total
9000/(n+5) = number of boxes each worker handles


rate*time = amount done
(37.5 boxes per day)*(20 days) = 9000/(n+5)
37.5*20 = 9000/(n+5)
I'll let the student solve that equation. You should arrive at <font color=red>n = 7</font> which is the number of extra workers you should hire so you finish 28 days early.


More practice found <a href="https://www.algebra.com/algebra/homework/proportions/Proportions.faq.question.1208740.html">here</a>
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