6) (a) Show that p q and (p q) (p q) are logically equivalent. (3 marks)

(b) Show that p (q r) and q (p r) are logically equivalent. (4 marks)

7) Show that each of these conditional statements is a tautology by using truth tables:

(a) (pq)q (2 marks)

(b) (pq) q (2 marks)