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 (-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:

Step1: Analyze each option

• Option A: Days can't be negative in this context. The number of days is 7, not -21.
• Option B: The number of books can't be negative in a real - world sense. The library has some non - negative number of books initially and loses 21 books.
• Option C: Since 3 books are loaned out each day (negative change per day as books are leaving) and for 7 days, the total change in the number of books is \((-3)\times7=-21\). This means the change in the number of books at the library over the week is -21.
• 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 \(-21\).