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. Loan - out days are positive.
• Option B: A library can't have a negative number of books in a practical sense.
• Option C: Since 3 books are loaned out each day (\(-3\) represents books loaned out per day) for 7 days, \((-3)\times7=-21\) represents the total change (decrease) in the number of books over the week.
• Option D: The number of books loaned per day is \(3\), not \(-21\). The \(-3\) in the equation represents the rate of change (books loaned out) per day.

Answer:

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