Don't understand why people don't like math its like the easiest stuff ever. Just follow the rules and you get there.
Edit:a better way to see your profit you can use this: ounces of weed =(x) (x X 27) - (x X 6) - 12= the Profit of the weed. I think this is better to see what your profit is for the first round of selling weed after that you can use this: Ounces of weed=(x) (x X 27) - (x X 6).