finding Ic3 and Ic4 are not difficult to do because of the current mirror load. you need the transconductance to find differential gain but I'm not sure whether or not to include the output impedance of the transistors.
The question and my attempt have been provided in the attachments...my problem is trying to find the differential gain, i have worked through to an answer but the answer I'm getting doesn't seem correct...also i have absolutely no idea how to derive the common-mode gain...any help is much...