Posted by Andrea B on Wednesday, June 13, 2012 at 2:28pm.
let the amount of the 5% solution that must be added be x gallons
.05x + .10(20) = .08(20+x)
times 100
5x + 10(20) = 8(20+x)
5x + 200 = 160 + 8x
-3x = -40
x = 40/3
they should add 13 1/3 gallons of the 5% solution.
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