Question

a library loans out 3 books every day for a week and no books are returned. the equation below is written to represent the situation: (-3)·7 = -21 which description best explains the meaning of -21 in the equation? a books were loaned out for -21 days. b the library now has -21 books. c the change in the number of books at the library over the course of the week was -21. d the number of books loaned per day was -21.

Explanation:

• Option A: Days can't be negative in this context. Loaning out for -21 days is not logical.
• Option B: A library can't have a negative number of books in a real - world sense (books are physical objects and the count starts from 0).
• Option C: Since 3 books are loaned out each day (a decrease, represented by - 3) for 7 days, the total change in the number of books (which is a decrease) is \((-3)\times7=-21\). This is a valid interpretation of the result of the multiplication as a change.
• Option D: The number of books loaned per day is 3, not -21. The - 3 in the equation represents the rate of decrease per day.

Answer:

C. The change in the number of books at the library over the course of the week was \(-21\).