The numbers from one to nine taken three at a time formulate 63 combinations. Of these numbers 1,3,5,7,9 are odd and the rest 2,4,6,8 are even. The even numbers taken two at a time must be paired in a particular way 2,6 and 4,8. If paired 2,8 and 4,6 then the number 5 has to be used two times to make the rows equal to 15. So let's complete the two rows 8,3,4 and 6,7,2. The remaining numbers formulate the third row 1,5,9. Now we have the 3 rows.

8 3 4

1 5 9

6 7 2

All the columns and the rows sum to 15. __https://mycalcu.com/__

15 as a sum of 3 different numbers in the range 1..9.

** **

These are: 1+5+9, 1+6+8, 2+4+9, 2+5+8, 2+6+7, 3+4+8, 3+5+7, 4+5+6.