How are up-votes and comments weighted? What makes a post more valuable than another one?

Hi SteemIt community. Need your insight. How are up-votes and comments weighted? I see two articles that have the same amount of up-votes and/or comments yet one has been rated more valuable than the other. Why is that? In fact, I've seen one article that had 50 votes and was worth $9 while another article with 30 votes was worth $.08?

Thanks in advance for the help!