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 cannot be negative in this context. The number of days is 7 (a week), so this is incorrect.
• Option B: A library can't have a negative number of books in a real - world sense. The negative sign here represents a change, not an absolute quantity of books.
• 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 is \((-3)\times7=-21\). This option correctly interprets the meaning of - 21 as the change in the number of books.
• Option D: The number of books loaned per day is 3 (represented as - 3 in the equation to show a decrease), not - 21.

Answer:

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