Question

the difference between a two-digit number obtained by interchanging the two-digits of the number in 9. if the sum of the two digits of the number is 15 that what is the original number?​

Answer 1

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

Then, x+y=15 ……….(i)

Given number: 10y+x

Interchanged digits: 10x+y

A.t.Q:-

⇒(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.