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If A U B is a subset of A intersect B, then prove that A=B

Now i can see this in my head and it makes sense that the elements in set A and Set B would have to be the same. The problem that i have with subset questions is how to prove that this is the case. I can start by saying

For all x ( x is an element of (A U B) --> x is an element of (A intersect B))

( x is an element of (A U B) --> x is an element of A AND B))

( x is an element of (A U B) --> x is an element of A AND x is an element of B))

Where do i go from here??? Any help would be great

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# Homework Help: More set theory

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