<PRE><B>Question 305285</B>
    How many ounces of water should be evaporated from 90 ounces of a 10% salt solution in order to make a 15% salt solution
.
Let x = ounces of water evaporated
then
.10(90) = .15(90-x)
9 = 13.5 - .15x
9 + .15x = 13.5
.15x = 4.5
x = 4.5/.15
x = 30 ounces
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