Proof the proposition.

For this question. I have no idea how to start.

The P(I) just messes me up.

Since J belongs in the set P(I), shouldn't the statement be ⊆ instead of the top one?

which is all K ∈ I, X∈ Sk

which is all K ∈ J, X∈ Sk

Some hints to get me start the question would be helpful. Thank you.