Question

A number consists of 2 digits whose sum is 9. If 27 is substracted from the number its digits are reversed. Find the original number.

Answer 1

Let us assume the digits be x and y

Then the two-digit number is 10x + y

Given x + y = 9

           y = 9 – x ----------------1

Given (10x + y) – 27 = 10y + x

             9x – 9y = 27

                x – y = 3 ----------------2

Substitute the value of y from eqn 1 in eqn 2

Therefore, x – (9 – x) = 3

                     2x = 12

                      x = 6

Therefore, y = 9 – 6 = 3

The two-digit number is 10x + y = (10*6) + 3 = 63