Answer:
3 cups of vinegar
Step-by-step explanation:
∵ Nick uses the amount of vinegar for every 1 cup of olive oil = [tex]\frac{1}{4}[/tex] cup
∴ He will need the amount of vinegar for 12 cups of olive oil = [tex]\frac{1}{4}\times 12[/tex] cups
= 3 cups
Therefore, Nick will need 3 cups of vinegar to make salad dressing.