The first step is to calculate the amount of brown sugar needed for one batch of cookies. Carolyn's recipe calls for 1 3/4 cups of brown sugar for each batch of cookies.
Next, we need to calculate how many batches Carolyn is making. She is making 2 1/2 batches of cookies in total.
To find out the total amount of brown sugar needed, we multiply the amount of brown sugar needed for one batch by the total number of batches.
So multiply 1 3/4 cups of brown sugar per batch by 2 1/2 batches.
The result of this multiplication will give us the total amount of brown sugar needed. After performing the multiplication we find that Carolyn needs 4.375 cups of brown sugar to make her 2 1/2 batches of cookies.