SOLUTION: 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

Algebra ->  Matrices-and-determiminant -> SOLUTION: 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       Log On


   



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(13198) About Me  (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(52775) About Me  (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                      = %286000-12%2A200%29%2F60 = 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.