Final answer:
Sarah should use 2.25 cups of flour for each batch of cookies as determined by dividing the total flour needed by the number of batches.
Step-by-step explanation:
The question asks how many cups of flour Sarah should use for each batch of cookies if the recipe requires 9 cups of flour for four batches. To find the amount of flour per batch, we divide the total amount of flour by the number of batches.
9 cups of flour ÷ 4 batches = 2.25 cups of flour per batch.
Therefore, Sarah should use 2.25 cups of flour for each batch of cookies.