Ok this is how it works:
Gang A wants to gs Gang B
so GA(Gang A)vs GB
now, Lets say GA had 5000 gang score
now GB wins and they get a certain % of it e.g after GB Wins
GA:4300
GB:3899
Now, I do not know the correct statistics for it... but :
If GA Wins they will win a small % again that would be :
GA:4500
GB:3650
So usually the Loser Loses Score and the Winners Take it