Hahah this is very very old man. People cracked this one a long time ago.
A two-digit number would be "10x + y"
Add the two digits (x+y)
Substract it from original number = 10x + y - (x+y) = 9x
Pick any 1 digit number and multiply it by 9. You will see all of them have the same image. And that's what the actual number is.
So, no matter what number you choose from the list, the answer will always be that one particular image (9.x).