Answer:
1/4 cups of flour per serving
Step-by-step explanation:
There are a couple of missing data in the question. The complete question says: A recipe calls for 1 1/2 cups of flour, 3/4 cup of white sugar, and 1/3 cup of brown sugar.
Knowing that there are 1 1/2 cups of flour in 6 servings, to get how many cups of flour are there per serving, you need to divide the cups of flour by the number of serving to get:
1 1/2/6 = 1/4 cups of flour per serving
This means that in, for example, 4 servings, 1 cup of flour will be needed (this result is gotten multiplying 1/4 by 4)