The direct process of calculation is a bit complex to explain at the outset.
From your test / clone instance, you can download the package: fabalrepb.pls and check for Procedures like:
- get_adjustments, which calculates the Adjustments performed, using FA_ADJUSTMENTS etc tables
- get_balance, which calculates the Balances, using FA_DISTRIBUTION_HISTORY etc.
You will get a clear idea on the tables and the way the values are calculated.