Question

the digits of a two digit number differ by 5 if the digits are interchanged and the resulting is added to the original number then we get 99 find the original number

Answer 1

here's the solution
Let us assume, the x and y are the two digits of a two-digit number.
Therefore, the two-digit number = 10x + y and reversed number = 10y + x
Given:x - y = 5 -------------1
Also given:10x + y + 10y + x = 9911x + 11y = 99x + y = 9 --------------2
Adding equation 1 and equation 22x = 14x = 7
Therefore, y = x - 5 = 7 - 5  = 2Therefore, the two-digit number = 10x + y = 10*7 + 2 = 72