In order for a BJT to operate as an amplifier, the base-emitter junction must be forward-biased and the base-collector junction must be reverse-biased. This is called forward-reverse bias.
Also: BJT MCQ Quiz
The three currents in the BJT transistor are the base current (IB), emitter current (IE), and collector current (IC).
The correct mathematical relationship between transistor currents is:
Transistor currents: IE = IC + IB
Also see: How to Test a BJT Transistor using Digital Multimeter