**8- 4- 5- 9**

primes- 2,3,5,7, composites- 4,6x,8,9, neither prime not composite- 0,1

excluded - 6 as per condition 1, so three of composite numbers are 4,8,9 as per condition 6

9 is the last and 8 is the first, because the fourth numbers must be the greatest of four as per condition 3.

4 must be second, if it is the third, then 9-4=5 and 8-5=3, makes the order 8,3,4,9 but first and last two numbers must be both even or both odd as per condition 4.

8,4,x,9

x=9-(8-4)=5

**8,4,5,9 meets all conditions**