Question

A number consists of two digits whose sum is $8$. If $18$ is added to the number, its digits are interchanged. Find the number.

• A. $53$
• B. $35$
• C. $92$
• D. $63$

Answer 1

The correct option is B $35$

The number is $10x+y$
When digits are reversed, the number becomes $10y+x.$
We have,
$x+y=8$ ....(1)
$10x+y+18=10y+x$
$x-y+2=0$ ....(2)
Solving (1) and (2), we get
$x=3,y=5$
$\therefore$ the number is $35$.