Problems based on Numbers Test 2

Let the unit number = x
Ten’s digit number = y
Then the original number formed = 10 x + y
Reversal of the original number = 10y + x
New number subtracted from the original number
$\left(10\mathit{y}+\mathit{x}\right)-\left(10\mathit{x}+\mathit{y}\right)$
$10\mathit{y}+\mathit{x}-10\mathit{x}-\mathit{y}$
$9\mathit{y}-9\mathit{x}$
$9\left(\mathit{y}-\mathit{x}\right)$
The resultant number will always divisible by 9.