Here's what Mathematica gets:
Thank You.
I was about to start typing that to Reduce which I installed yesterday but you got there first and Mathematica seem very nice with that equation editor. Anyway, very impressive.
There is another set of 8 resistors that are in circuit with each other on the hybrid. However, four of those are JFETs so I'll just lift some JFET pins or remove them instead of writing eight equations to solve for the values.
But this technique looks to be good in solving resistor networks measured in-circuit.
The hybrid in question is a YHP multislope AD-converter part, used in many YHP products. This one is from 4284A LCR meter. The resistor chains discussed above provide HI, LO and ZR (as in zero) comparator levels for the integrator. LO and ZR are actually taken from the integrator with gain so that their actual tripping point could be set low enough.
This ADC system also includes a PAL for which the read result is attached.
For schematics of the hybrid application, see for example 4278A service manual.