Question

The sum of the digits of a two-digit number form 1 to 9 is 8. If 9 is added to the number, then both the digits become equal. Find the number.

Answer 1

Answer:

Let the two digit number be xy

x+y=9

yx+9=3(xy)

10y+x+9=3(10x+y)

x+10y+9=30x+3y

29x=7y+9

y=9−x

29x=7(9−x)+9

36x=63+9

36x=72

x=2

x+y=9

y=9−2=7

Original number =27