SOLUTION: This word problem has me stumped. Can you help? How much water must be evaporated from 240 gallons of a 3% salt solution to produce a 5% salt solution?

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Question 10912: This word problem has me stumped. Can you help?
How much water must be evaporated from 240 gallons of a 3% salt solution to
produce a 5% salt solution?
Answer by rapaljer(4671) About Me  (Show Source):
You can put this solution on YOUR website!
Let x= number of gallons to be evaporated (removed) from the solution.

240 = no of gallons to begin with at 3%
-x = no of gallons to evaporate at 0%
240-x = no of gallons to end up with at 5%

Equation:
.03(240) - 0(x) = .05(240-x)
7.2 = 12 - .05x
7.2 - 12 = 12- 12 - .05x
-4.8 = -.05x
x+=+%28-4.8%29%2F%28-.05%29+=+96 gallons
Leaving behind 240-96 = 144 gallons

Check:
+240+%2A+.03+=+144%2A.05
7.2+=+7.2

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