SOLUTION: How many gallons of a 50% anti-freeze solution must be mixed with 90 gallons of 25% anti-freeze to get a mixture that is 40% anti-freeze?

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Question 462897: How many gallons of a 50% anti-freeze solution must be mixed with 90 gallons of 25% anti-freeze to get a mixture that is 40% anti-freeze?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
How many gallons of a 50% anti-freeze solution must be mixed with 90 gallons of 25% anti-freeze to get a mixture that is 40% anti-freeze?
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Equation:
anti + anti = anti
0.50x + 0.25*90 = 0.40(x+90)
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Multiply thru by 100 to get:
50x + 25*90 = 40x + 40*90
10x = 15*90
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x = 135 gallons (amt. of 50% solution needed)
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Cheers,
Stan H.
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