Final answer:
The expression that shows how many bags of snack mix are left unsold is s - 12.
Step-by-step explanation:
The expression that shows how many bags of snack mix are left unsold is s - 12.
Since 12 out of s bags of snack mix were sold, we can subtract 12 from the total number of bags to find out how many are left unsold. The expression s - 12 represents this.
For example, if there were 20 bags of snack mix in total, and 12 were sold, then we have 20 - 12 = 8 bags left unsold.