Fill-in-the-blank proofs for Section 3.3

1. Claim: For all sets A and B, (A ∩ B) ⊆ A.
   Proof. Click here.
   
2. Claim: For all sets A and B, B ⊆ (A ∪ B).
   Proof. Click here.
   
3. Claim: For all sets A and B, if A ⊆ B, then (A ∪ B) ⊆ B.
   Proof. Click here.
   
4. Claim: For all sets A, B and C, if A ⊆ B and A ⊆ C, then A ⊆ (B ∩ C).
   Proof. Click here.
   
5. Claim: For all sets A, B and C, (A ∩ B) ∪ (A ∩ C) ⊆ A ∩ (B ∪ C).
   Proof. Click here.