Analog Electronics Circuit
Since this is homework, I'm not going to outright answer it.

First go look up something known as a emitter follower and understand it.  Note that you have two emitter followers, one capable of driving the output high, the other low.

To not get confused by the two transistors, start by analyzing with only one in the circuit at a time.  Assume V1 is 2 V and the bottom transistor isn't there.  What happens.  Now add the bottom transistor.  How does that change things, if at all?