Please show steps and explanations.

Counting passwords: Consider the following sets of characters: Letters: L = {a, b, c, d, e, f, g. h, i, i, j. k. l, m, n, 0. p, q, r, S. t, u, v. w, x, y, z}(26 elements) Decimal digits:D = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9} (10 elements) Passwords can be any strings whose characters are either letters or digits included in L U D Compute the number of passwords that satisfy the following additional constraints: 9. Password length 7 or 8 and contains no repeated characters: ans h. Password length 10 and contains no repeated characters, and has exactiy one digit: ans i. Password length 10 and contains no repeated characters, and has at least one digit: ans j. Password length 10, no repeated characters, and includes either the digit \"1\" or \"2\" or both: ans