SOLUTION: How many quarts of water need to be added to 30 quarts of 40% alcohol to obtain a 20% alcohol solution?

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Question 342922: How many quarts of water need to be added to 30 quarts of 40% alcohol to obtain a 20% alcohol solution?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
In order to halve the concentration, double the volume of water.
Add 30 quarts of water.
Algebraically, here's the concentration equation,
Let A be the amount of water added.
Water is a 0% alcohol solution.
0%28A%29%2B40%2830%29=20%28A%2B30%29
1200=20A%2B600
20A=600
highlight%28A=30%29quarts