Question 1169635
Johnny needs 10 liters of a 15% acid solution. He currently has a 10% solution and a 30% solution. How many liters of 10% solution does he need to make the needed 10 liters of 15% acid solution?
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He currently has --- why not just "he has" ----  Currently is not needed.
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x = amount of 10% to use
y = amount of 30%
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x + y = 10 ---- total solution
10x + 30y = 10*15 ---- total acid
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Solve for x & y