1. Divide the first term of the numerator by the first term of the denominator, and put that in the answer. 2. Multiply the denominator by that answer, put that below the numerator. 3. Subtract to create a new polynomial.
If it's a hearty soup that is served as the meal itself, and served with bread or crackers and salad, then you can figure about 2 cups per person. Since there are 16 cups to a gallon, that would give you 8 servings. If it's a lighter soup that is served as part of a 5 - 7 course meal, then you can figure about 1 cup person, which would be 16 servings.