The formulas should be in the rules. There are really a lot of factors you'll have to consider such that the easiest method is merely to find individuals who own income facilities on that planet or check for listings on CPM from that planet for ideas how much certain income facilities seem to be making. You'll start to get a feel for what a good income facility makes, depending on which kind it is. As for a city, well it depends on how you design it based on access, terrain and other special considerations.
I understand what you're asking because there was a time I was looking for the same kind of information. I also understand that the rules present only basic knowledge on the subject. This is a general questions forum but IC information can't be provided here. I would ask some of your friends, or feel free to contact myself via DM, and I'll share what I know on the subject.
The uberman simpleman formula for an income city (if that's your goal): 1.5 total ER value / 4 offices, 4 taverns, 4 hotels, 2-3 garages / no labor camps, no slave markets, no over-proliferation of parks. Whatever else you can fit. Voila!
Another question. It's second time it happends to me. My facilities did almost 500k profit, I was informed about that fact in the inventory menu, BUT the money never came to me :( I have screenshots if someone won't believe me. All facils are powered and the rest is set like the rules say. I don't know why the reason of this :( It should be working fine :( Where is my money :(