D.J. MacHale's purpose after writing the book Sylo Chronicles is that people should not succumb to peer pressure.
The theme of a story is the message that the author passes across to the readers. It's the main point in a story. In this case, the theme of the story is that people should not succumb to peer pressure.
In the story, it can be deduced that the death of Marty was because she succumbed to peer pressure. Mr. Feit pushed her in collecting the ruby and she eventually died as a result. Even if other people are doing something bad, we should not join them.
Read related link on:
brainly.com/question/25335844
Affect - someone causing something.
Effect - the result of what was caused.
EX: Destroying trees negatively affects the wildlife.
EX: The effect that destroying trees has on wildlife is negative.