RF choke value calculation for a LNA bias circuit

Can anyone help with the below:

I know that the choke value is supposed to be 10X the magnitude of the reactance at the point where choke is going to be connected in LNA bias-circuitry. I have included a circuit:

a) Conjugately matched LNA amplifier

b) Conjugately matched LNA amplifier with bias circuit with choke values.

How where these choke values 20 and 200nH determined i.e. how was the impedance determined at that point on the circuit order to work out reactance which in turn was used to calcuculate inductance.

My hunch was that the reflection coefficient at the load and source after matching were determined and these were used to work out impedance at source and load from which reactance was determined. I however do not get he same answer with this approach

Probably my answer is not correct due to unable to understand the problem.
To start the design for conj match step a is start point.
Step b required to ensure not to disturb match drastically but still able to provide the required bias.
I guess if you change the value 20 to 200 then it should work fine( no effect on impedance match).
However there is important point called stability.
Some time design need to trade off with matching to have un-conditional stability.

I agree with you regarding the above. However my question specifically is:

How do you determine the reactance at the point where the de-coupling/coupling caps and choke inductors are connected?

Because once you have calculated the reactance then the inductor/cap values are easily worked out.