Enter numeric values without units and symbols. If the answer is 19 code words, enter 19 as your answer. How many two-element subsets does the set {A, B, C, D, E, F, G, H, I, J, K, L} have? How many two-letter code words can be formed by using the letters A, B, C, D, E, F, G, H, l, J, K, L if repetition is allowed? How many two-letter code words can be formed by using the letters A, B, C, D, E, F, G, H, l, J, K, L if repetition is NOT allowed