The empty set is a subset of every set

THEOREM 2    The empty set is a subset of every set. PROOF     Let A be any set and ϕ be the empty set.ln order to show that ϕ ⊆ A,we must show that  every element of ϕ is an element of A also. But ϕ contains no element.  So,  every  element  of ϕ…