<PRE><B>Question 271615</B>
How many liters of water containing 4 grams of salt per liter must be combined with x liters of water which contains y grams [y is less than 2] of salt per liter to yield a solution with 2 grams of salt per liter.
 need equation in x and y


4gram solution-------------------  y grams solution---------------- 2 gram mix

-------a ------------------------------ x liters-------------------- a+x


Let the quantity of 4 gram solution added be a

4a + xy = 2(a+x)

4a= 2(a+x) -xy

a= 2(a+x) -xy  / 2

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