Question

sum of the digits of a two digit no is 9 by interchanging the places of digits the number reduced by 63 find

Answer 1

Let’s say x is the unit digit and y is the tenth digit.

y+x = 9 -> y=9-x

10x+y = 10y+x+63

10x+9-x = 10(9-x)+x+63

10x+9-x = 90–10x+x+63

18x = 18

x = 1

so y = 8

The number is 81