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IS MY ANSWERS CORRECT?
Let S be the universal set, where:
S={1,2,3,...,18,19,20}
Let sets A and B be subsets of S, where:
Set A={1,2,4,5,8,9,11,12,15,16,17,18,20}
Set B={2,5,6,7,8,12,14,16,19,20}
LIST the elements in the set (A∩Bc) = { the answer I have is
4,9,11,15,17,18
LIST the elements in the set (B∩Ac) = { the answer I have is 1,6,7,14,19
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
S = {1,2,3,...,18,19,20}
A = {1,2, 4,5, 8,9, 11,12, 15,16,17,18, 20}
B = { 2, 5,6,7,8, 12, 14, 16, 19,20}
Bc = {1, 3,4, 9,10,11, 13, 15, 17,18 } <<<--- see how I formed the set Bc.
It is a necessary intermediate part of the solution.
Then
(A n Bc) = {1, 4, 9, 11, 15, 17,18} <<<--- me, ikleyn
the answer I have is
{ 4, 9, 11, 15, 17,18} <<<--- you, the author
I am very glad that you followed my advise and made your part of the work.
Your work is good. Almost perfect !
But, what is even more important, you did it on your own and, I hope, learned something useful and got some new skills.
! Congratulations !
Now I can communicate with you as with equal partner.