Counting numbers are to be formed using only the digits 1, 8, 3, 5, 4, 9. Determine the number of different possibilities for two-digit numbers.

Just list all of them like this

1. 18

2. 13

3. 15

4. 14

5. 19

6. 83

7. 85

8. 84

9. 89

10. 35

11. 34

12. 39

13. 54

14. 59

15. 49

15 numbers x 2 = 30 numbers for the opposite for example 94 instead of 49.

30 is your answer