<PRE><B>Question 184451</B>
You need a 40%saline solution for an experiment, but only have 25% saline and 75% saline solutions. How much of each would you have to combine to create 50ml of 40% saline solution? 
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Equation:
salt + salt = salt
0.25x + 0.75(50-x) = 0.40*50

Multiply thru by 100 to get:

25x + 75*50 - 75x = 40*50

-50x = -35*50

x = 35mL (amt. of 25% solution in the mixture)

50-x = 15mL (amt. of 75% solution in the mixture)
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Cheers
Stan H.</PRE>