16. Show that pq and (pq)(pq) are logically equivalent. 17. Show that (pq ) and pq are logically equivalent. 18. Show that pq and qp are logically equivalent. 19. Show that pq and pq are logically equivalent. 20. Show that (pq) and pq are logically equivalent. 21. Show that (pq) and pq are logically equivalent. 22. Show that (pq)(pr) and p(qr) are log ically equivalent. 23. Show that (pr)(qr) and (pq)r are log ically equivalent. 24. Show that (pq)(pr) and p(qr) are log ically equivalent. 25. Stow that (pr)(qr) and (pq)r are log ically equivalent