Question 450999
let the tens digit be x, y the ones digit.  Then x+ y = 9, and 

10x + y - 27 = 10y + x.

The second equation is equivalent to 9x - 9y = 27, or x - y = 3.

Combining this with the first equation, we get x = 6, and y = 3.  

The original number is 63.