The problem can be solved in different ways.
Applying a rule of three we have:
6 servings ---------------> 2-quart pot
x ---------------------------> 12-quart pot
Clearing the value of x we have:

Using ratios can also be solved in two ways:
Way 1:
Service relationship to quart pot:

Clearing f we have:

Way 2:
Relationship of quart pot to services:

Clearing f we have:

Answer:
The two methods are correct.