Question 1159320
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Jotham needs 70 liters of a 50% alcohol solution. He has a 30% solution and an 80% solution available. 
How many liters of the 30% solution and how many liters of the 80% solution should he mix to make the 50% solution?
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<pre>

Let x = the volume of the 80% solution needed, in liters.

Then the volume of the 30% solution to mix is  (70-x) liters.


The equation to find x is THIS


    0.80x + 0.30*(70-x) = 0.50*70,  


It says that the volume of the pure alcohol in ingredients is equal to the volume of the pure alcohol in the final mixture.


From this equation, express x and calculate

    x = {{{(0.50*70-0.30*70)/(0.80-0.30)}}} = 28.


<U>ANSWER</U>.  28 liters of the 80% solution and the rest, 70-28 = 42 liters, of the 30% solution.
</pre>

Solved.