Question 1046146
A 1 qt. mixture of alcohol and water is 95% alcohol. The mixture is to be reduced to 40% alcohol. Determine amount of distilled water to be added. 



A clear way to think of it is  {{{(amountAlcohol)/(amountMixturePlusamountAddWater)=ConcentrationAlcoholDesired}}};
and your variable will be amountAddWater or amount of water to add to the mixture.


{{{(1*0.95)/(1+v)=0.4}}}, which is written using decimal fractions instead of percents.  The amount of water to add is assigned as v.


SOLVE this equation for v.



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There is a decimal mistake in the steps you asked about.  Stepping through mine just two ,

{{{0.95/(v+1)=0.4}}}

{{{0.95=0.4(v+1)}}}

{{{0.95=0.4v+0.4}}}