Don't need to do question 3

Problem 3: Proof of Equalities (25) Consider sets A,B, and C, and: 1. (5) Prove (AB)(ABC) by universal generalization. 2. (5) Prove (ABC)(AB) by universal generalization. 3. (5) Prove (AC)(CB)= by membership table. 4. (10) Prove (BA)(CA)=(BC)A by universal generalization, applied twice to use the double-subset property