SOLUTION: four pencils and five pens cost $2.00. Three pencils and four pens cost$1.58. Find the cost of a pencil and the cost of a pen
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Question 254027: four pencils and five pens cost $2.00. Three pencils and four pens cost$1.58. Find the cost of a pencil and the cost of a pen Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! four pencils and five pens cost $2.00. Three pencils and four pens cost$1.58. Find the cost of a pencil and the cost of a pen
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Equations:
4n + 5p = 200
3n + 4p = 158
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Multiply thru the 1st equation by 3
Multiply thru the 2nd equation by 4
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12n + 15p = 3*200
12n + 16p = 4*158
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Subtract the 1st equation from the 2nd and solve for "p":
p = 4*158-3*200
p = 32 cents (cost of a pen)
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Substitute into 4n + 5p = 200 to solve for "n":
4n + 5*32 = 200
4n + 160 = 200
4n = 40
n = 10 cents (cost of a pencil)
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Cheers,
Stan H.
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