SOLUTION: Please help. There are 12 elements in the intersection of sets A and B, and there are 20 elements in the union of sets A and B. If set A has 4 fewer elements than set B, find the n

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Question 946209: Please help. There are 12 elements in the intersection of sets A and B, and there are 20 elements in the union of sets A and B. If set A has 4 fewer elements than set B, find the number of elements that are in set B, but not set A. Thanks for your help.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
They share 12 in common.
With all of them together they have 20.
4 of the additional items comes from A not in B.
So the remaining items must come from B not in A.
12%2B4%2BX=20
X=4
So there are 4 items in B not in A.