Finding a current in a given circuit
Redrawing things can sometimes help a little. Here's how I might attempt to redraw your schematic:







simulate this circuit &ndash; Schematic created using CircuitLab

Note that you have 5 equations and 5 unknowns. (Substitution could reduce that, if you like.) A quick check suggests that you will find two equally valid answers for the problem, though. You should also find (in both cases) that \$I_\text{B}\$ is negative (goes opposite to the indicated arrow.)