Respuesta :

6 is 

6/16, 9/16, 12/16, 15/16

8 is

16/18, 15/18, 14/18, 13/18

I hope this helps! If you want I can elaborate :)
6) 3/8,9/16,3/4,15/16
8) 8/9, 5/6, 7/9, 13/18