The sum of the digits of a two digit number is 9 If the digits were reversed the new number would be 9 more than the original number Find the original number?

Possibility of two digit no whose sum is 9

18,27,36,45,54,63,72,91

Now add 9 to each no mentioned above

27,36,45,54,63,72,91,100

See after third comma 45 and 54. If you reverse 45 it will be 54. which is 9 more than 45. So original no is 45