Question

A number consist of two digits whose sum is 9 If 9 is subtracted from the number its digit are interchanged find the numbers​

Answer 1

Let the number be XY

The value of the number is 10X+1Y

Given that 9 is subtracted from the number

10X+Y-9

Given that the digits interchange it becomes YX

The Value of the number is 10Y+X

10X+Y-9=10Y+X

9X-9Y=9.......(1)

X-Y=9

X=9+Y

The numbers are 21 and 12