Question 221109
How many gallons of an 8% acid solution and a 22% acid solution need to be mixed to make 14 gallons of a 13% acid solution?
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Equation: 
acid + acid = acid
0.08x + 0.22(14-x) = 0.13*14
Multiply thru by 100 to get:
8x + 22*14 - 22x = 13*14
-14x = -9*14
x = 9 gallons (amt. of 8% solution in the mixture)
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14-x = 5 gallons (amt. 22% solution in the mixture)
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Cheers,
Stan H.