SOLUTION: how many gallons of water need to be added to convert 2 gallons of 30% acid solution into a 20% acid solution?

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Question 421064: how many gallons of water need to be added to convert 2 gallons of 30% acid solution into a 20% acid solution?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let w = gallons of water needed
given:
acid in 2 gallons of 30% solution is .3%2A2+=+.6
+.6%2F%282+%2B+w%29+=+.2+
+.6+=+.2%2A%282+%2B+w%29+
+.6+=+.4+%2B+.2w+
+.2w+=+.6+-+.4+
+.2w+=+.2+
+w+=+1+
1 gallon of water must be added
check:
+.6%2F%282+%2B+1%29+=+.2+
+.6%2F3+=+.2+
.6+=+.6
OK