hi
There is a difference of 6.
3.455 (3 and 91/200)13/4 = 26/8Halfway between 26/8 and 30/8 is 28/8 = 3.5
the difference between them is 4 and 5/8.
8, 11, 14, 17, 20, 23 and 26
The difference between 13 and 5 is 8. 13 - 5 = 8 (check sum is 8 + 5 = 13)