'How do I add a where claus in wolframalpha

I want to ask a set theory question to woframalpha with a where clause. For example,

((A intersection f1) intersection B)  union (A intersection (B intersection f2))
where f1 is subset of A
      f2 is subset of B

How do I add such a clause in the wolframalpha website? Is this possible at all?

wolframalpha

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