Question

For any two sets A and B, prove that 

A ⊂ B A ∩ B = A

Answer 1

Let 

p ϵ A ⊂ B. 

⇒ x ϵ B

 Let and p ϵ A ∩ B 

⬄ x ϵ A and x ϵ B 

∴ (A ∩ B) = A.