In my case, I was doing this symbolically trying to derive equations in terms of variable resistance values to use in SPICE simulations. With Mathcad or some other symbolic capable mathematics package that also includes matrix math that would be relatively easy, but the equations were simple enough that I just set about doing it by hand figuring it would be faster than figuring out how to get some unfamiliar tool to do it (I may have been wrong about that). I ended up just using old fashioned linear system of equations substitution, and then later realized the entire thing could be solved a lot more simply based on the symmetry of the circuit.

Like I said, dumber every year I get further away from college. :-)