Question 1183872
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We want to have  x-y  maximum.


Under given condition, it happens when  x  is maximum possible and  y  is minimum possible.


According to this scheme,  x= 4, y = 1  is the  UNIQUE  solution.


<U>ANSWER</U>.  x= 4, y= 1  and the difference  x-y  is 3.

         Maximum  x-y  is  4-1 = 3.

         Option D.
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Solved.