For this case we will pose an equation according to the amount of cookies left after Anna ate 8.
So:
If I bake 3 batches of cookies and each batche had "c" cookies, then we have:
.
IF Anna ate 8 we have:
![3c-8](https://img.qammunity.org/2020/formulas/mathematics/middle-school/4hx9q7i4q7ixgrlo3otb14reeuo7wl6kaw.png)
Thus, equation 3c-8 represents the amount of cookies left after Anna ate 8.
ANswer:
![3c-8](https://img.qammunity.org/2020/formulas/mathematics/middle-school/4hx9q7i4q7ixgrlo3otb14reeuo7wl6kaw.png)