I am having problems with this problem.In the mythical kingdom of Permutatus, wizards have special 2-digit license plats, The first digit is greater than 6, and the second digit is odd. The two digits cannot be the same, How many different license plates are possible.

Answer 1

No. of digits > 6 : {7,8,9} i.e. 3 of them
odd digits: {1,3,5,7,9}, i.e. 5
Total = 3×5 = 15
However, subtract number of plates with identical digits. Figure out which plates there are and calculate the final numbers.