Can You Escape The 100 Room VIII Level 36 Walkthrough

what is the logic the circles with the letters. how to get the words ?
Please help to solve this puzzle !

No logic for circle puzzle.😡😡

Thank you so much 😎👌

I think if you match the letter (first line) on the out circle + the letter (third line) on the inner circle, you got the letter in second line (center of the inner circle)
D + X = U
O + G = S
G + G = A
With the same logic + keyword DOGDOGDO (the seconline), you got OPENDOOR (the first line).

How did you get to the password opendoor? It's not clear.