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avatar+105 

If a farmer can trade four chickens for a p*g, three pigs for two sheep, and five sheep for two cows, what is the minimum number of cows he needs to trade for 20 chickens?

 Nov 11, 2018
 #1
avatar+107405 
+1

Let

Chickens  = x

Pigs  = y

Sheep = z

Cows =  w

 

So

4x = 1y    ⇒  y = 4x 

3y = 2z   ⇒  3(4x)  = 2z ⇒   12x  = 2z  ⇒  6x = z

5z = 2w   ⇒  5(6x)  = 2w  ⇒   30x  = 2w ⇒  15x = 1w

 

So

 

1w / 15x   =     ?w / 20x

 

1 / 15  =  ? / 20

 

20 / 15  =   ?   =  4/3 cows for 20 chickens

 

 

cool cool cool

 Nov 11, 2018
 #2
avatar+20239 
0

4 b /p     3/2 p/s    5/2 s/c   = 15 b/c      (birds per cow)  

 

20 b /  15 b/c = 1 1/3 c      ~~~ He will need to trade 2 cows

 Nov 11, 2018

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