Question 48862
\let x be the 10 digit and let y be the one digit
original number = 10x+y
reversed = 10y+x
x+y=12
y=12-x (subsitution)


10y+x=15+10x+y
10(12-x)+x=10x+12-x
120-10x+x-9x=12
-18x=-108
x=6
y=12-6
y=6
Hence, the number is 66
Paul.