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

18,27,36,45,54,63,72,81

Now add 9 to each no mentioned above

27,36,45,54,63,72,81,90

See after third comma 45 and 54. Reverse of 45 is 54. 54 is 9 more than the no 45.

So 45 is original