Finding the missing number

Solution:
-Ignore the middle numbers (3,5,8,8,?)
- Add the side numbers and divide by 2
- You will get the middle number as answer!

 Solution:

4(3)2= [4+2 /2 = 3]

5,3(5)1,1= [5+3+1+1 /2 = 5]

6,1,2(8)3,3,1= [6+1+2+3+3+1 /2 = 8]

7,2(8)4,3= [7+2+4+3 /2 = 8]

9(?)3= [9+3 /2 = 6]