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 the 40% solution should the chemist use?

Question 648118: 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 the 40% solution should the chemist use?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = liters of 40% solution needed
Let = liters of 20% solution needed
= liters of salt in 40% solution
= liters of salt in 20% solution
------------
(1)
(2)
---------------------------
(2)
(2)
(2)
---------------------
Multiply both sides of (1) by
and subtract (1) from (2)
(2)
(1)

and, since
(1)
(1)
(1)
12.5 liters of the 40% solution are needed
check:
(2)
(2)
(2)
(2)
(2)
OK

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