Question

the sum of the digit of a two digits number is 12. the number obtained by interchanging its digits exceed the given number by 18.find the number.

Answer 1

Let the digit in the number is xy.

So number is 10x + y

Given

sum of the digits of a two-digit number is 12

=> x+ y = 12..........................1

Again

10y + x = 10x+ y +18

=> 10y + x - 10x - y = 18

=> 9y -9x = 18

=> y - x = 2 ..................2

Solving equation 1 and 2, we get

x = 5, y = 7

So the number is 57.