SOLUTION: a radiator holds 12 qt of liquid. How many quarts of pure antifreeze and how many quarts of 40% antiffreeze solution must be mixed to fill the radiator with a 50% antifreeze soluti

Question 346060: a radiator holds 12 qt of liquid. How many quarts of pure antifreeze and how many quarts of 40% antiffreeze solution must be mixed to fill the radiator with a 50% antifreeze solution?
Found 2 solutions by stanbon, Fombitz:
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
a radiator holds 12 qt of liquid. How many quarts of pure antifreeze and how many quarts of 40% antiffreeze solution must be mixed to fill the radiator with a 50% antifreeze solution?
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Equation:
anti + anti = anti
0.40x + 1.0(12-x) = 0.50(12)
Multiply thru by 100 to get:
40x + 1200-100x = 50*12
-80x = -600
x = 60/8 = 15.2 = 7.5 quarts (amt. of pure antifreeze needed in the mixture)
12-x = 4.5 quarts (amt. of 40% solution needed in the mixture)
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Cheers,
Stan H.

Answer by Fombitz(32388) (Show Source): You can put this solution on YOUR website!
Let be the amount of pure antifreeze and the amount of 40% solution.
Total amount equation:
1.
Concentration equation:

2.
Multiply eq. 1 by (-2) and add to eq. 2,

quarts
Then from eq. 1,

quarts
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