Answer:
1293 soccer books
Step-by-step explanation:
The tricky part about questions like this is: how do I assign variables to the three types of book?
You get a clue from the sentence, "She sold 3 times as many copies of the soccer book as the baseball book." The number of soccer books is being described by referring TO the number of baseball books. Pick a variable and assign it to the item being REFERRED TO!
x = number of baseball books
Then 3x = number of soccer books. The number of basketball books is the same, so 3x = number of basketball books. Here's the list...
x = number of baseball books
3x = number of soccer books
3x = number of basketball books
The total of these is 3017, so
x + 3x + 3x = 3017
7x = 3017
x = 431
Ah! But don't forget to look back at the question: it asks for the number of SOCCER books! That's 3x, so 3(431) = 1293.
