Question 1184009
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How many quarts of pure antifreeze must be added to 5 quarts of a 30% antifreeze solution 
to obtain a 50% antifreeze solution 
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            In my previous post,  I gave a detailed description of the solution procedure to a  TWIN  problem in word form.

            THEREFORE,  I will omit here all the words and will present the solution in short form.



<pre>
The basic equation is


    {{{(x + 0.3*5)/(x+5)}}} = 0.5


    x + 0.3*5 = 0.5*(x+5)

    x + 1.5  = 0.5x + 2.5

    x - 0.5x  = 2.5 - 1.5

      0.5x    = 1.0

         x    = {{{1.0/0.5}}} = 2.


<U>ANSWER</U>.  2 quarts of the pure antifreeze must be added.


<U>CHECK</U>.   {{{(2 + 0.3*5)/(5+2)}}} = {{{3.5/7}}} = {{{1/2}}} = 0.5 = 50%    ( ! correct concentration ! )
</pre>

Solved.