<PRE><B>Question 213292</B>
How many gallons of a 4% acid solution should be mixed with 30 gallons of a 13% acid solution to obtain a mixture that is 7% acid?
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Equation:
acid + acid = acid
0.04x + 0.13*30 = 0.07(x+30)
Multiply thru by 100 to get:
4x + 13*30 = 7x + 7*30
3x = 6*30
x = 2*30 = 60 (amt. of 4% solution needed for the mixture)
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Cheers,
Stan H.</PRE>