SOLUTION: How many gallons of a 3% salt solution must be mixed with a 7% salt solution to obtain 100 gallons of a 5% salt solution?
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Question 305557: How many gallons of a 3% salt solution must be mixed with a 7% salt solution to obtain 100 gallons of a 5% salt solution?
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!
Let 
represent the number of gallons of 3% solution. Then the gallons of pure salt in the 3% solution must be 
. The number of gallons of 7% solution, given that we need 100 gallons overall, must be 
, and the number of gallons of pure salt in the 7% solution must be )
. And finally, there has to be 5 gallons of pure salt in 100 gallons of 5% solution.
\ =\ 5)
If you multiply by 100 you get integer coefficients -- much neater:
\ =\ 500)
Just solve for .
John
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