SOLUTION: I have 20 gallons of a solution that is 40% alcohol, If I want to end up with 20 gallons of a 60% alcohol solution then how much pure alcohol would I have to add? HINT: If you add

Question 264004: I have 20 gallons of a solution that is 40% alcohol, If I want to end up with 20 gallons of a 60% alcohol solution then how much pure alcohol would I have to add? HINT: If you add x number of gallons of pure alcohol, you first must take away x number of gallons of the 40% solution.
I have figured out the answer is 4 gallons, I just am not sure how to lay out the problem.
Answer by JBarnum(2146) (Show Source): You can put this solution on YOUR website!
"I have 20 gallons of a solution that is 40% alcohol"
.4(20)=8 gallons of alcohol and 12 gallons of solution
.6(20)=12 gallons of alcohol and 8 of solution
12gallons - 8 gallons makes 4 gallons more needed of alcohol, but if you just add 4 more gallons you get 24gallons so u have to subtract 4 gallons first and then add 4 pure alcohol
i cant seem to get an equation for it, maybe someone else can help out
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