Prove that A ⊆ B, B⊆ C and C⊆ A ⇒A = C.

We have $A \subseteq B, B \subseteq C$ and $C \subseteq A$

Now , A is a subset of B and B is a subset of C, So A is a subset of C.

Given that $C \subseteq A$.

Hence, A = C.