Verified Answer :

Nizux

18 |16 | 13 | 10 | 9.5 | 8.5 | 7.5 | 6
                      
9.75 is the FINAL answer

you have to fist pot them in order 6,  7.5,  8.5,  9.5,  10,  13,  16,  18

so the middle numbers are 9.5 and 10 

add them together 9.5+10=19.5 then divide by 2 so 19.5/2=9.75  that is you answer