Answer:
12.5 cups used
7.5 cups left
Step-by-step explanation:
Number of batches = 5
Cups of flour per batch = 2 1/2 cups
Initial amount of flour = 20 cup bag
After 5 batches ; number of cup used :
5 * 2 1/2 = 12.5 cups of flour
Change in amount of flour in bag :
(20 cups - 12.5 cups) = 7.5 cups