Question

please tell me what is the answer ​

Answer 1

Step-by-step explanation:

let the digit be a and b.

a+b=13

number= 10a+b

after 9 added, the number becomes= 10b+a

10a+b+9= 10b+a

9a+9=9b

a+1= b

a=6 and b= 7