Question 272631
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How many quarts of pure antifreeze must be added to 6 quarts of a 10% solution to obtain a 20% antifreeze soltuion? 
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<pre>
Let x be the volume of pure antifreeze to add, in quarts.


Then the governing equation is 

    x + 0.1*6 = 0.2(x+6)    <<<---===  the amount of the pure antifreeze in ingredients (left side)
                                       and in the mixture (right side)


Simplify and find x

    x + 0.6 = 0.2x + 1.2,

    x - 0.2x = 1.2 - 0.6,

      0.8x   =    0.6,

         x   =    0.6/0.8 = 6/8 = 3/4 = 0.75.


<U>ANSWER</U>.  0.75 quarts of pure antifreeze should be added.
</pre>

Solved correctly.