Question

The sum of the digits of a two digit number is 15.The number obtained by interchanging the digits exceeds the given number by 9. find the number​

Answer 1

Answer: The number is 78

Explanation:

Let the units digit be x and tens digit be y.

x + y = 15

(10x+y)−(10y+x)=9

10x+y−10y−x=9

⇒9x−9y=9

x−y=1 ………(ii)

Solving (i) and (ii)

x=8, y=7

∴ Two digit number=78.