Question 349506
Let A be the amount of 100% alcohol.
Let B be the amount of 0% alcohol (water).
{{{A+B+25=50}}}
1.{{{A+B=25}}}
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{{{100A+0B+72(25)=56(50)}}}
{{{100A+1800=2800}}}
{{{100A=1000}}}
{{{highlight(A=10)}}}
Then from eq. 1,
{{{highlight(B=15)}}}
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10 quarts of pure aloohol and 15 quarts of pure water need to be added.