Okay, here are the steps to solve this problem:
* The recipe calls for 3/4 teaspoon of cinnamon for every 4 cups of granola mix.
* So for 1 cup of granula mix, you need 3/4 / 4 = 3/12 teaspoon of cinnamon.
* For 12 cups of granula mix, you would need 12 * (3/12) = 3 teaspoons of cinnamon.
Therefore, for 12 cups of granola mix you would need 3 teaspoons of cinnamon.