How much water must be added to a gallon of alcohol 75% pure to make a mixture 15% pure ?(adsbygoogle = window.adsbygoogle || []).push({});

The book I'm reading has given this formula : 0.75/(n+1)= 0.15 while n is the number of gallons to be added.

I don't understand where the heck the formula comes from

Can you help me with this problem ?

Thanks

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# Homework Help: Algebra and %

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