Question 630933
a chemist has two acid solutions in stock: one that is 40% solution and the other 60% solution. How much of each solution should be mixed to obtain 100ml of a 45% solution? 
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f = amount of 40%
s = amount of 60%
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f + s = 100 (total solution)
40f + 60s = 45*100  (total acid)
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