Question 724863

Determine the sets A, B where 

A - B = {1, 3, 7, 11}
<pre>
From that we have:

 1 &#8712; A,   1 &#8713; B
 3 &#8712; A,   3 &#8713; B
 7 &#8712; A,   7 &#8713; B
11 &#8712; A,  11 &#8713; B 

B - A= {2, 6, 8}, 

From that we have:

 2 &#8712; B,   2 &#8713; A
 6 &#8712; B,   6 &#8713; A
 8 &#8712; B,   8 &#8713; A

A &#8745; B = {4, 9}

From that we have:

 4 &#8712; A,   4 &#8712; B,   9 &#8712; A,   9 &#8712; B 

So we end up with

A = {1,3,7,11,4,9}, B = {2,6,8,4,9}

----------------------------------------
</pre>
 C - D = {1, 2, 4},
<pre>
From that we have:

 1 &#8712; C,   1 &#8713; D
 2 &#8712; C,   2 &#8713; D
 4 &#8712; C,   4 &#8713; D

D &#8722; C = {7, 8}, 

From that we have:

 7 &#8712; D,   7 &#8713; C
 8 &#8712; D,   8 &#8713; C

C &#8746; D = {1, 2, 4, 5, 7, 8, 9}

Since 5 and 9 are not in either C - D or in D - C,
they must be elements of both sets, since they were
removed in both cases of set subtraction.  Therefore

C = {1,2,4,5,9},  D = {7,8,5,9}

Edwin</pre>