SOLUTION: A chemist is mixing a 40% salt solution with a 20% salt solution to make 50 L of a new solution that will contain 25% salt. How much of each of the original solutions should the ch

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Question 481593: A chemist is mixing a 40% salt solution with a 20% salt solution to make 50 L of a new solution that will contain 25% salt. How much of each of the original solutions should the chemist use?
I know the answer from a answer key but can you show me how its doen.
Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
A chemist is mixing a 40% salt solution with a 20% salt solution to make 50 L of a new solution that will contain 25% salt. How much of each of the original solutions should the chemist use?
.
Let x = amount (L) of 40%
then
50-x = amount(L) of 20%
.
.40x + .20(50-x) = .25(50)
.40x + 10 - .20x = 12.5
.20x + 10 = 12.5
.20x = 2.5
x = 12.5 L of 40% solution
.
20% solution:
50-x = 50-12.5 = 37.5 L of 20% solution