There is no absolute rule about that comma. Follow your style guide, text book or teacher.
http://english.stackexchange.com/questions/412/should-i-put-a-comma-before-the-last-item-in-a-list
i have a question
say you're writing a sentence such as "I ate apples, bananas, oranges, and grapes." is there a comma before 'and' or no?
2 answers
oh kk thanks!