The library sells 376 books at its annual used-book fundraiser, taking in a total of $2120. Children's books cost $4, and adult books cost $7. How many children's books did they sell?
Let \( c \) = number of children's books sold, and \( a \) = number of adult books sold.
Which system of equations can the librarians use to solve this problem?
A.
\[
\begin{align*}
4c + 7a &= 376 \\
c + a &= 2120 \\
a &= 376 - c
\end{align*}
\]
B.
\[
\begin{align*}
7c + 4a &= 2120 \\
a + c &= 376
\end{align*}
\]
C.
\[
\begin{align*}
4a + 7c &= 2120 \\
c + a &= 376
\end{align*}
\]
D.
\[
4c + 7a = 2120
\]
Answer (2)
Answer: \left\{\begin{array}{ccc}4a+7c=2120\\a+c=376\end{array}\right
To solve the problem, we establish a system of equations based on the revenue and total number of books sold. The correct choice is option C, which states the equations: 4 c + 7 a = 2120 and c + a = 376 . This allows for solving the number of children's books sold efficiently.
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