Answer:
45
Step-by-step explanation:
we know the number is two digits.
we know that the sum of the digits is 9
therefore, the only possible numebrs are:
18, 81
27, 72
36, 63
45, 54
we also know that the inverse of the digits is the original number plus nine
therefore, 18 and 81 are out
27 and 72 are out
36 and 63 are out
the only numbers left are 45 and 54.
since 45+9=54, the number is 45.
