Determine which formula pairs are equivalent. If equivalent, prove it using the laws of equivalence and mention the laws used at each step. If it is not equivalent, give an interpretation that makes the truth value different. a. r^(pq) V (q r) and (r p) ((pq) ^r) b. (ps) V (r^rVp ^-q) ^ (q r) and p V-q VrVs c. (pr) ^ (q p) ^ (r p) andp ^r V p^r Determine whether the following proposition is a tautology, contradiction, or satisfiable and explain why! ( ~a b c) ( c) {[(-a V b) A a] V b} (c b) V (b c) {(-ab) + (~a ^ ~c) ^ b} ( c) a. b. c.