Question

micheal stone won the National junior Olympics award so he was so happy he wrote a dariy entry
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Answer 1

Explanation:

usual, prove it using the general heuristic that

X=YX=Y if and only if X⊆Y and X⊇Y.X⊆Y and X⊇Y.

X=YX=Y if and only if X⊆Y and X⊇Y.X⊆Y and X⊇Y.In other words, take a generic element of A×(B−C)A×(B−C) and show that it also must be an element of (A×B)−(A×C)(A×B)−(A×C), and vice versa.