math help please help me ??

X + Y = 60 and
4X + 1Y = 2*60.
Therefore X = 20 and Y = 40.
Answer A.

Let h represent the number of quarts of high-percent milk. Then the total butterfat in the final mix is
.. 4%*h + 1%*(60 - h) = 2%*60
.. 3%*h + 1%*60 = 2%*60 ... eliminate parentheses, collect terms
.. 3%*h = 1%*60 ... subtract the constant on the left
.. h = 60*(1%/3%) = 20 ... divide by the coefficient of h

Answer A is the best choice.
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You notice that the average of the two sources is 2.5% and the mix has lower butterfat than that. This means the amount of 1% must be greater than the amount of 4%. Only one answer meets that requirement. No other calculation is required for a multiple choice question like this.