Question 287986
I need to get my truck serviced. The maintenance guy said the anti-freeze in my radiator is at 25% solution and I only have about 4 gallons in the radiator. 
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It needs to be at 50% solution for the winter. The anti-freeze that he has is a 100% solution. 
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How many gallons of 100% anti-freeze should be mixed in the 25% solution to bring it up to a 50% solution?
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Equation:
alcohol + alcohol = alcohol
0.25*4 + 1*x = 0.50(4+x)
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Multiply thru by 100 to get:
25*4 + 100x = 50*4 + 50x
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50x = 25*4
x = 2 gallons (amount of 100% solution needed for the mixture)
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Cheers,
Stan H.