?

Someone is asking for my help, and it's been way to many years since I've been in school for this.

Here is the problem. I have 5 resistors in a network such that no two are either in series or parallel, so those rules won't work. I'm looking for the total resistance between points A and B.

Here is the circuit.

http://img.photobucket.com/albums/v74/puppy_raiser...

What I know.

If the 400 ohm resistor were an open R total would be 900 ohms and if a short, 600 ohms, so with 400 ohms (or any other value), the answer must be between 600 and 900.

What I think I remember.

It seems to me, you have to assume a voltage or current someplace, then using ohms law calculate other values, finally coming up with 3 equations and 3 unknowns. Solving for the 3 unknowns with basic algebra skills gives a quick path to the answer, but coming up with the 3 equations or even what the 3 unknowns are escapes me. Any help out there (with how you did it) would be much appreciated.