Have some coffee first
If everyone in the room is DR A, yours the lowest at 30,000 the rest between 30,000 and 50,000 you would gain between 80 and 120 points per player you finish ahead of, and lose between 80 and 40 points per player that finishes ahead of you.
You secret formular is 80 +/- (DR difference / 500) per player. min 1, max 160.
Finish ahead of a player you take 80 + ((their DR - your DR) / 500)
Finish behind a player you give 80 + ((your DR - their DR) / 500)
If the DR difference is 40,000 or more then you would only lose 1 point per player that finishes ahead of you, yet gain 160 points if they crash or disconnect.
You always lose points when you finish last, unless you are at DR 1 already.