I got a cascade amplifying system
I gotta calculate v_out/v_in

I don't understand the approach of the solution. So if it was a voltage controlled voltage source I would do (v_i2 / v_i1) * (v_out / v_i2), but this is current controlled current source which confuses me a bit. I made a red ring around partially of the solution, I assume that's the v_out calculated by voltage division. I am not sure of the rest if someone could break it down it would be nice.
ty.