Question 1143037
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Here is a non-algebraic way to solve mixture problems like this that will get you to the answer much faster and with far less work than the standard algebraic method show by the other tutor.<br>
Picture the problem as starting with 5% alcohol and adding 25% alcohol and stopping when the mixture is 16% alcohol.  The problem is easily solved by modeling the percentages on a number line and seeing what fraction of the way from 5% to 25% you go before you stop at 16%.<br>
On the number line, the distance from 5 to 25 is 20; the distance from 5 to 16 is 11.  That means 16% is 11/20 of the way from 5% to 25%.<br>
And that means 11/20 of the mixture is the 25% alcohol that you are adding.<br>
ANSWER: 11/20 of 20 gallons, or 11 gallons, is the 25% alcohol; the other 9 gallons is the 5% alcohol.