I deleted one of my answers because it had a score of -1 which brought a -2 reputation penalty to me. However, instead of gaining 2 reputation, I lost 6 reputation. What is going on?
Link to question here: Is C minor i in the key of C minor?
An upvoted answer gives you 10 rep. A downvoted answer gives you -2.
It looks like that answer had one upvote and two downvotes - a net +6 rep. When you deleted it you lost that +6.
One of the privileges you will hit at 1000 rep is the ability to see the vote counts on posts: If you ever need to know how many up- and downvotes you have on a post, click on the post score, and it will split out the totals for you.