SOLUTION: You need to strengthen a 25% alcohol solution with a pure alcohol solution to obtain a 70% solution. How much pure alcohol should you add to 100 milliliters of the 25% solution?

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Question 1046116: You need to strengthen a 25% alcohol solution with a pure alcohol solution to obtain a 70% solution. How much pure alcohol should you add to 100 milliliters of the 25% solution?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = ml of pure alcohol to be added
+.25%2A100+=+25+ ml of pure alcohol in the 25% solution
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+%28+x+%2B+25+%29+%2F+%28+x+%2B+100+%29+=+.7+
+x+%2B+25+=+.7%2A%28+x+%2B+100+%29+
+x+%2B+25+=+.7x+%2B+70+
+.3x+=+45+
+x+=+150+
You need 150 ml of pure alcohol
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check:
+%28+x+%2B+25+%29+%2F+%28+x+%2B+100+%29+=+.7+
+%28+150+%2B+25+%29+%2F+%28+150+%2B+100+%29+=+.7+
+175+%2F+250+=+.7+
+.7+=+.7+
OK