Answer:
528 cookies
Step-by-step explanation:
3 hours is 180 minutes
55 minutes - the 15 for preheating is 40 minutes
180 minutes + 40 minutes = 220 (total time she could've had cookies in the oven)
220 divided by 20 is 11 (total batches of cookies)
11 times 48 is 528
Sorry if my answer is confusing lol