Question 498263
Do it like this one.  Only the numbers are different.
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a solution of 78% alcohol is to be mixed with a solution of 23% alcohol to form 165 liters of a 58% solution.  How many liters of the 78% solution must be used?
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s = amount of 78%
t = amount of 23%
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s + t = 165 (total solution)
--> t = 165 - s
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0.78t + 0.23s = 0.58*165 (total alcohol)
Sub for t
0.78s + 0.23(165-s) = 0.58*165
78s + 3795 - 23s = 9570
55s = 5775
s = 105 liters of 78%