Question

katys class visited the bookfair this afternoon. she bought a set of m books from her favorite mystery series and a set of 4 books from her favorite science fiction series. katy bought 9 books in all.
which diagram models the story?
diagrams showing two models with m, 4, and 9
which equation models the story?
options: ( m - 4 = 9 ), ( m + 4 = 9 )

Explanation:

Part 1: Which diagram models the story?

Katy bought \( m \) mystery books and 4 science - fiction books, with a total of 9 books. The diagram should represent the sum of \( m \) and 4 equal to 9. In the second diagram, the total length (representing total books) is 9, and it is split into two parts: \( m \) (mystery books) and 4 (science - fiction books), which matches the story. The first diagram has 9 and 4 as parts with a total of \( m \), which does not match the story.

Step 1: Analyze the quantities

Katy has \( m \) books from the mystery series and 4 books from the science - fiction series. The total number of books she bought is 9.

Step 2: Form the equation

To find the total number of books, we add the number of mystery books (\( m \)) and the number of science - fiction books (4). So the equation is \( m + 4=9 \). The equation \( m - 4 = 9\) would imply that she has 4 more mystery books than the total, which does not match the story.

Answer:

The second diagram (the one with total 9, split into \( m \) and 4)

Part 2: Which equation models the story?