Well, what's the procedure for finding a Thevenin equivalent when the network in question contains no independent sources, just dependent ones?
I'll give away one hint: A voltage source bordering two loops effectively presents a barrier between the loops. The controlled source that separates the two loops in this problem isolates interactions between the loops by anything except that source.
In other words, you can ignore R2 entirely since the controlled source will produce whatever voltage it is called to produce regardless of load, and R2 is just a fixed load.
