SOLUTION: How many gallons of pure alcohol should be mixed with 20 gallons of 15% alcohol solution to obtain a mixture that is 25% alcohol?

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Question 213620: How many gallons of pure alcohol should be mixed with 20 gallons of 15% alcohol solution to obtain a mixture that is 25% alcohol?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = gallons of alcohol to be added
In words:
(original alcohol + added alcohol)/(total mixture) = 25%
%28.15%2A20+%2B+x%29%2F%2820+%2B+x%29+=+.25
3+%2B+x+=+.25%2A%2820+%2B+x%29
3+%2B+x+=+5+%2B+.25x
.75x+=+5+-+3
.75x+=+2
x+=+2.67
2.67 gallons of alocohol must be added