This was done by multiplying 2 by 3 since 3 thirds (3/3) make one whole.
So if 2 teaspoons are used for 1/3 teaspoon of salt, 4 teaspoons would be used for 2/3 teaspoon of salt and 6 teaspoons would be used for 1 teaspoon of salt.
2 or 2.4 because 3 quarts is 12 cups. Now if you want to make while servings you can make 2 whole servings. But for the usage of all cups you would make 2.4 servings