The Answer is Never- Hope this helps and have a great day!
Step-by-step explanation:
We are given that set A⊂B .
This means that set A is properly contained in set B.
i.e. A≠B
This means that there are some elements in set B which are not in set A.
Now we have to show whether the following property A∩B=A∪B
always, sometimes or never hold.
As A is a proper set of B.
This means that: A∩B=A ( Since A is a smaller set)
Also, A∪B=B (Since B is a bigger set)
Hence, A∩B ≠ A∪B (Since A≠ B)
Credit to -virtuematane