Final answer:
To find out how many fliers Ann still has not posted, subtract the number of fliers she has already posted from the total number of fliers she had initially. Ann still has 0 fliers left to post.
Step-by-step explanation:
To find out how many fliers Ann still has not posted, we need to subtract the number of fliers she has already posted from the total number of fliers she had initially.
Ann started with 42 fliers. She posted 13 of them last week, so she had 42 - 13 = 29 fliers remaining at the beginning of this week.
This week, Ann posted 57 fliers. Therefore, the number of fliers she still has not posted is 29 - 57 = -28 fliers.
However, negative fliers do not make sense. So, Ann still has 0 fliers left to post.