Question

A no. consists of two digits whose sum is 9. if 27 is subtracted from the no. the digit interchange their places. find the no.

Answer 1

Let x and y are the two digits of a two-digit number.

Given, x + y = 9  ---------------- (1)

   and 10x + y - 27 = 10y + x.    ----------- (2)

           = 9x - 9y = 27

           = x  - y = 3.

 Adding (1) and (2), we get

 2x = 12

  x = 6

Therefore y = 9 - 6 = 3.

The original number is 63.