The sum of a two

Let the one’s digit be ‘a’ and ten’s digit be ‘b’

Given, sum of two-digit number and the number formed by reversing the order of digits is 99.

⇒ 10a + b + 10b + a = 99

⇒ a + b = 9

Also, digits differ by 3.

⇒ a – b = 3 or b – a = 3

Adding both equation

2a = 12 or 2b = 12

⇒ a = 6 and b = 3 or a = 3 and b = 6

Number can be 36 or 63