Answer:
45
Step-by-step explanation:
Let the original number be xy where y is unit and x is tens hence original number is 10x+y When reversed, the new number is yz hence 10y+x
We know that the original number plus 9 is the reversed number hence
10x+y+9=10y+x
9y-9x=9 which when simplified we obtain that
y-x=1 equation 1
Originally, we are told that the sum of x and y is 9 hence
y+x=9 equation 2
Solving equation 1, it means y=x+1
Substituting the above into equation 2
x+1+x=9
2x=9-1
2x=8
x=8/2=4
Since y=x+1 then y=4+1=5
Therefore, the original number, xy is 45
