(no issue)Actual marble cost does not match the basic costs after discount

Server: Ares Global 1

According to the help menu, the marble cost for upgrading a town hall to level 20 is "35,187".
The actual marble cost that I need for upgrading from level 19 to 20 is "27,003".

My level 20 Architect's office shows the following statistics:
- Basic costs: 100.00%
- Research (14.00%): 86.00%
- Architect's office (20.00%): 66.00%

Assuming that the help menu's "35,187" is the basic costs, calculating the expected cost after discount does not result in "27,003":
35187 * 66% = 23223.42 ≠ 27003

Calculating the actual basic cost:
Unknown base cost * 66% = 27003

27003 / 66% ≈ 40913.64

How do you determine that 27,003 should be the actual cost?

Confusing that the help section does not mention that research reductions are included. Anyways, thank you for the explanation