[sdiy] A little OT, Begging a hand

[David G. Dixon]

> > I'm pretty sure your problem is underdetermined. Here's my reasoning:...

Sorry, I misread the original problem.  The voltages are known and the
resistances are unknown.  In that case, the problem is underspecified, as
Ian says.  There are six unknowns (R1, R2, R3, R4, R5 and R8) and still only
four equations (current balances at four nodes).  This implies that there is
no unique solution to the problem.  Two resistor values must be specified to
bound the problem, but those two values cannot be R1 and R8 together, as
this will leave only three equations for four unknowns.