7. Determine if the following expressions are tautologies, contradictions, or contingencies by using truth tables. Show all your work. (10.0 marks) a. (p V q) v ( +9) b. (p =-9) --(p1-9) c. ((q -p) v (q^p)) - (p^ p) 8. Determine if the following expression is a tautology, a contradiction, or a contingency by using the logical equivalences. You may not use a truth table. Show all your work, labelling each rule used, and do not skip any steps. (4 marks) a. (a - b Vc)) (Gb + c) a)