Question 1179803
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The solution method used by the other tutor is very good (and faster and easier than the standard formal algebraic method).  But in my opinion the presentation of the method could be better.<br>
Here is the same solution using different wording.<br>
The target 4% is 2/3 of the way from 2% to 5%; that means 2/3 of the mixture must be the milk with 5% butterfat.
Since 120 gallons of the 4% milk are to be produced, 80 gallons must be the 5% milk and the other 40 gallons must be the 2% milk.<br>