Question

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

Answer 1

Let us assume, x and y are the two digits of a two-digit number.
Therefore, the two-digit number = 10x + y and the reversed number = 10y + x

Given:
x + y = 9 ---------1

Also given:
10x + y - 9 = 10y + x
9x - 9y = 9
x - y = 1 -----------2

Adding equation 1 and equation 2
2x = 10
x = 5

Therefore, y = 9 - x = 9 - 5 = 4

Therefore, the two digit number = 10x + y = 10*5 + 4 = 54

Answer 2

Your answer is above