If a ≡ b(mod k), that is if a is congruent to b in modulo k, the congruence relation is formally written a = kn b. Show that if a ≡ c(mod n), b ≡ d(mod n). Show your work. i. a b ≡(c d)(mod n). ii. a − b ≡ (c−d)(mod n). iii. a × b ≡ (c×d)(mod n)