Question 455868
How many quarts of a 20% alcohol solution and how many quarts of pure alcohol should be mixed together to obtain 100 quarts that contain 30% alcohol?

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Equation:
Quantity Equation:: x + y = 100 quarts
Alcohol Equation:: 0.20x+y = 0.30*100
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Multiply thru 1st by 20
Multiply thru 2nd by 100
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20x + 20y = 20*100
20x +100y = 30*100
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Subtract and solve for "y":
80y = 10*100
y = 100/8 = 12.5 quarts (amt of pure alcohol needed)
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Solve for "x":
x + 12.5 = 100
x = 87.5 quarts (amt of 20% alcohol needed)
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Cheers,
Stan H.
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