Question Number 104850 by ~blr237~ last updated on 24/Jul/20

Let  E be a no empty set with card=n≥1   Find in term of  n      Σ_(A,B⊆E) Card(A−B)=Σ_(A,B⊆E) Card(A∩B)=(1/3)Σ_(A,B⊆E) Card (A∪B)=n4^(n−1)