Answer:
6 and 9
Explanation:
We can write out all possible numbers
1 and 14 (difference is 13, not 3) X
2 and 13 (difference is 11, not 3) X
3 and 12 (difference is 9, not 3) X
4 and 11 (difference is 7, not 3) X
5 and 10 (difference is 5, not 3) X
6 and 9 (difference is 3, checks out!) ✔
7 and 8 (difference is 1, not 3) X