Finding the equivalant impedence of a circuit
As John D points out: you can do a Delta to Y conversion. Or Y to Delta.  That is where you take a set of three resistors (or impedances) and convert them to three other values.

His link points to the wikipedia where they use all resistors. But instead of R you can use a Z and it will still work.







simulate this circuit &ndash; Schematic created using CircuitLab

In the schematic above you e.g. take Z2, Z3 and Z5 (That is a Y-formation or T-formation) and make them into a Delta Za, Zb Zc. 







simulate this circuit

I assume you can take it from there.