Question 381751
Let the digits of the number be x and y.
So the number is xy (note: this does not mean x times y).
x+y=7 and yx=xy+9
In order for yx to equal xy+9, x=y-1.
Now we have the two equations x+y=7 and x=y-1.
x+y=7 -> x=7-y
y-1=7-y
2y=8
y=4
Plug that into one of the original equations: x+4=7
x=3
The number is 34.