SOLUTION: How many mL of 95% alcohol are needed to prepare 60 mL of 30% alcohol

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Question 734581: How many mL of 95% alcohol are needed to prepare 60 mL of 30% alcohol
Answer by josmiceli(19441) About Me  (Show Source):
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Let +a+ = ml of 95% alcohol needed
+.95a+ = ml of alcohol in 95% solution
Let +b+ = ml of water needed
(1) +a+%2B+b+=+60+
(2) +.95a+%2F+60+=+.3+
--------------------
(2) +.95a+=+18+
(2) +a+=+18.947+
18.947 ml of 95% alcohol is needed