Can someone answer it pls

What numbers are included in the set of integers? what numbers are not included?

With this question, the answer with the red arrow is incorrect!

Edith is shopping for a new leather couch. jordan’s furniture has one that costs $3,000. however, this weekend she can get a 15% discount. how much money will edith save if she buys the couch this weekend? a $15b $2,550c $45,000d $450