Back them up on a different drive
Answer:
Image result for who was eqvtime takaishvili?
Ekvtime Takaishvili (also spelled Taqaishvili) (Georgian: ექვთიმე თაყაიშვილი) (January 3, 1863 – February 21, 1953) was a Georgian historian, archaeologist and public benefactor was born January 3, 1863 in Likhauri and died February 21, 1953
There are ways to break into the boot cycle of every machine, you could use one of them. Hold down modifier key[s] so that it boots differently or you may get a menu to select boot options.
A specific answer is OS/firmware dependent.
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