Isolate k
C= 8+g∙k
How do you Isolate K by itself

k=(C-8)/g

Explanation:
Since our goal is to isolate k, we would have k on one side of the equal sign and everything else we move to the other. We do this by performing inverse operations to both sides (ex. The inverse of adding is subtracting and the inverse of multiplying is dividing).

C=8+gk
Subtract both sides by 8
C-8=8+gk-8
C-8=gk
Divide both sides by g
(C-8)/g=gk/g
(C-8)/g=k
k=(C-8)/g

I hope this helps!