SOLUTION: How much 25% solution must be added to 42 cc of pure water to make at most 20% salt solution?

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Question 924793: How much 25% solution must be added to 42 cc of pure water to make at most 20% salt solution?
Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
let x be the amount of 25% solution to add to the 42 cc of pure water, then we have the following table:
x .25 .25x
42 .00 0
x+42 .20 .20(x+42)
from the last column we have the following formula
.25x = .20(x+42)
.25x = .20x + 8.40
.05x = 8.40
x = 168 cc of 25% solution to be added to the 42 cc of pure water