Need help here. Please show me a detailed solution for this.

Here's the diagram:

http://www.flickr.com/photos/98820721@N04/92739068...

The phasor of current I1 is 2+3j[A], and the phasor of current I2 is 1[A].

1) Find the value of impedance Z.

2) Let the phase difference (arg(I3/I4)) between I3 and I4 be θ. Find the value of tan θ.