My hundreds digit is 3 more than my ones. My tens digit is I less than my ones. What number can I be?

Given that the hundreds digit is 3 more than the ones digit, and the tens digit is 1 less than the ones digit, the hundreds digit must be at least 4 and no more than 9. Therefore, the possible numbers are:

4 _ _
5 _ _
6 _ _
7 _ _
8 _ _
9 _ _

Since the hundreds digit is 3 more than the ones digit, to find the ones digit we subtract 3 from the hundreds digit:

4 _ 1
5 _ 2
6 _ 3
7 _ 4
8 _ 5
9 _ 6

Finally, as the tens digit is 1 less than the ones digit, to find the tens digit we subtract 1 from the ones digit:

4 0 1
5 1 2
6 2 3
7 3 4
8 4 5
9 5 6

Therefore, all possible valid numbers based on the constraints provided are:

401, 512, 623, 734, 845, 956