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Question 1145593:  You manage a clothing store and budget $6000 to restock 200 shirts. You can buy T-shirts for $12 each, polo shirts for $24 each, and rugby shirts for $36 each. If you want to have twice as many rugby shirts as polo shirts, how many of each type of shirt should you buy? 
 
 Found 2 solutions by  greenestamps, ikleyn: Answer by greenestamps(13215)      (Show Source): 
You can  put this solution on YOUR website! 
  
Let 
t = # of t-shirts, cost $12 each 
p = # of polo shirts, cost $24 each 
r = # of rugby shirts, cost $36 each
  
You manage a clothing store and budget $6000 to restock 200 shirts. 
(1) t+p+r = 200 
(2) 12t+24p+36r = 6000
  
If you want to have twice as many rugby shirts as polo shirts... 
(3) r = 2p
  
Substitute (3) into (1) and (2) to get two equations in t and p.
  
Then solve that pair of equations by your favorite method. 
 Answer by ikleyn(52903)      (Show Source): 
You can  put this solution on YOUR website! .
 
 
            From the first glance,  this problem is for  3  equations in three unknowns.
 
 
            But actually,  it can be easily solved using only  ONE  single equation in  ONE  unknown.
 
 
            I will show you how to do it.
 
 
 
Solution
 
 
Let  x be the number of polo shirts.
Then the number of rugby shirts is 2x, according to the condition.
And the number of T-shirts is then (200-x-2x) = 200-3x.
The total cost equation is then
    24*x + 36*(2x) + 12*(200-3x) = 6000.
Simplify and solve for x :
    24x + 72x + 12*200 - 36x = 6000,
    60x                      = 6000 - 12*200
      x                      =   = 60.
ANSWER.  60 polo shirts;  60*2 = 120 rugby shirts and the rest, (200-60-2*60) = 20 are T-shirts.
 
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The benefit of this approach is that students may start solving such problems much earlier than they start learning systems of equations.
 
 
I think that the true goal of this problem is to teach students to this approach.
 
 
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To see other similar solved problems, look into the lessons
 
    - More complicated word problems to solve using a single linear equation 
 
    - Advanced word problems to solve using a single linear equation
 
in this site.
 
 
 
 
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