So let's say? Give me a minute... Or hour.
Okay... On R34T2 I took 2 zones bordering me (neither with any city levels conquered) and a sea base. I had 99 resources to use. This move took 30 resources, and leaves me with 69 excess resources.
How do you find b in your calculations?
Anyhow, assuming you did it right (It looks right to me... you got 69 excess)... on R35T2 I could take 114 resources. I did the exact same move (not same zones, but same type). that left me with 84 excess resources.
You told me I could use 107 resources with 73 excess resources. Clearly you did something wrong there. Recalculating if you got b right... I could have taken 118. This time (R36T2) I really took the exact same zones. That's 30 more resources... 118-30 is 88.
For R37T2, you allowed me 147 resources, with only 76 of them excess form last turn. If you got b right... I calculate I could have taken 159. I again took the same zones, in addition to one that was 2 away from me where I took off the third level. This cost me 105 of my 159 resources. This left me with 54.
And finally, on R38T2... I used 80 resources to conquer that same city's hamlet... Which is inconsistent with what should have happened, because I should have used 90 resources. Somehow it skipped a level?
That's my analyzation of the past few of my moves.