User blog comment:Sirebel/Mathematician Required - Apply Within/@comment-26829117-20170423130833/@comment-31155082-20170423142812

The main problem coming to my mind at first glance is we don't have equations but inequalities (hope it is the correct word). We can suppose all the final PR are rounded down.

Just an example, supposing starting PR has a zero second decimal digit we only know:

0,1 + Bra1 <= 0,39 and 0,1 + Bra1 >= 0,30

then we can add the second upgrade and obtain other inequalities that can make the range for Bra1 smaller (maybe).

I don't even know if data provided can be enough to find a solution or only ranges of solution for every variable. It will be hard to find a way that can be used for every car.