Question

So I kinda know this but I still need a little help.

Answer 1

If the number is odd,
`u` can only be 1, 3, 5, 7 or 9.

If the number is less than 30,
`t` can be 1 or 2.

The sum of the digits has to be 10, so
`t` can't be 2, because it would lead to the number 28, which is even.

So,
`t` has to be 1, which implies that
`u=9`

In fact, the number 19:

• is odd
• the unit digit is greater than the tens digit (
  `9>1`)
• is less than 30
• the sum of its digits is 10