Question

The sum of the two digit of a two digit no is 12. If 18 is added to it, the digit are reversed. Find the no.

Answer 1

Let ab be a two digit number,

According to the question , a+b = 12
and ab + 18 = ba,

Writing numbers in expanding form, To get the answer,

=> a + b = 12, and 10a + b + 18 = 10b + a,
=>a + b = 12, and 9a + 18 = 9b,
=> Solving both the equations,
9a + 9b = 108, (Multiplied with 9)
9a + 18 = 9b,
Subtracting both the equations,

=> 9b - 18 = 108- 9b,
=> 18b = 126,
=> b = 7,

Substituting this in First equation , We get a = 5,

Verification :
In 57, 5+7 = 12, ✔
57 + 18 = 75, ✔

So both are satisfied,

Therefore the required number is 57,

Hope you understand !! Have a great day !