example shifted red 7 count for tc purposes

I just want some clarity if I am having this right. True counting red seven not using true edge just for study interest.

the formula according comrad is using 6 decks src=rc-12 For knowing the true count it is shifted running count (SRC/dr) in order to get the true count?

If by example using red seven starting at zero the rc is 16 than I subtract 12 makes 4/dr= TC?

anybody?

Thanks a lot