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A vat contains 60 gallons of a 15% saline solution. How many gallons of water must be evaporated so that the resulting solution will be 20% saline?

Verified Answer :

To solve this problem we can use proportion.
60 gallons -----------100%
x-------------------------15%
\(x= \frac{60*15}{100} = 9\) gallons of saline.
Now we can use this knowledge and create second proportion
9 galllons -------------20%
x-------------------------100%

\(x= \frac{9*100}{20}=45\) galloons
Now we can just find the difference (evaporated gallons)
60-45=15 - its our result.

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