Question 309994
how many gallons of a 10% alcohol solution be mixed with 20 gallons of a 10% acid solution to obtain an 8% acid solution? The answer is 40/3. How do you solve the problem?
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Equation:
alcohol + alcohol = alcohol
0.10x + 0.10*20 = 0.8(x+20)
Multiply thru by 100 to get:
10x + 10*20 = 8x + 8*20
2x = -2*20
x = -20
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The answer is unrealistic because the 
stated problem is unrealistic.  If 
you add 10% solution to 10% solution
you can never get 8% solution.
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Also, note you seem to be adding alcohol
and acid. Hmmmm!!!
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Cheers,
Stan H.