The administrator should set up an audit trail in order to get this information.
An audit trail would give him the record of all the configuration changes that have been made in a file or a database in the last 6 months.
Audit trails can be manual or electronic. It provides history and also documentation support. It can authenticate security and also help to mitigate challenges.
The gear ratios would look like A:B=1:9 and C:D=1:32 if you are just needing the gear teeth ratio. Not a lot of information to go off of from the question though
