The question is about the ownership of files on linux and who can edit them? [closed]

The question is about the ownership of files on linux and who can edit them? Let's say a file is owned by the user 'www-data' whose primary group is 'www-data' and the permissions on the file are '775'. If I am a member of the group 'www-data' can I read, edit and execute this file?

My understanding is that I should be able to do this.

Here is the directory listing of the file:

-rw-rw-r-- 1 www-data www-data 0 Mar 29 06:32 temp

Here is the list of groups I am in:

clive : clive adm cdrom sudo dip www-data plugdev users lpadmin docker

And here is what I get when I attempt to edit (vi) a file:

"temp" [readonly] 0 lines, 0 bytes

Confusing!