Question 244917
thirty liters of 40% alcohol solution is obtained by mixing 40% solution with a 70% solution. how many liters of each solution must be used to obtain the desired mixture
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I think you have made a mistake in posting your 
problem.  You don't mix a 70% solution with
a 40% solution to get a 40% solution.
No mixing would be necessary.
Cheers,
Stan H.