They shouldn't but many websites and apps do anyways. I wouldn't be surprised if Brainly was even using your data.
If you found information in a book as well as a website then use both. dont erase the page number cause you never know what youll need it for. sence your using a website youshould give cretit to the places you got your information from and the pae number will count as a resource so i would prefer you to keep it.
you kinda worded it weird so if my answer doesnt help then im sorry.
Answer:
The reason that Wilson thinks Gatsby killed Myrtle is because Tom told Wilson that Gatsby was the owner of the yellow car that had hit Myrtle. Wilson thinks that the reason as to why he killed her is because he didn't want to talk to her for the moment.
Explanation: