OK, here goes, it's pretty simple.
Let's say you have a 10 ring target target with an "X" ring on it.
And let's say that there are 5 clean holes centered in the scoring rings.
There is 1 in the 7 ring and that scores a 7
There are 2 in the 8 ring and that scores 16
There is 1 in the 9 ring and that scores 9
There is 1 in the 10 ring and that scores 10
Total for that target is the sum of each one = 42
So, let's change that up a bit
One of the 8 ring hits has cleanly cut the line between the 8 and 9 ring, so you would have 1 eight and 2 nines, increasing your score by 1 or now it is 43.
Now lets say that 10 ring shot hit in the x ring. You would still have 43, but now you would count the x so now it would be
43-x.
If another of your shots had been in the x ring also, the score would be 44-2X. If the 9 shot would have been an X hit, you would have 44-2X, regardless if it was a clean x shot or just cut the line.
Hope that helps,
John (Bigsmoke)