This is the source from the forums. Numbers seem to be different. The formulars have been in Scaredgirl´s wikipedia. Many of us might know, that Scaredgirl vanished and that this wikipedia is down.
If both scores are positive, it can be simplified to:
PvP 1 : 90 + 35 * opponents score / (opponents score + your score)
PvP 2: 150 + 35 * opponents score / (opponents score + your score)
EM: + 20 electum / + 30 electrum
Electrums are rounded down.
To lose score, you normally have to lose the same amount of electrums. If you win score, you normally gain the same amount of electrums. Abuse ? I don´t think so.