This is a new world for me, I haven't messed with circuits since physics 101. When I watched a quick youtube tutorial on setting up my Nest E, I thought it'd be a simple "move wire in old C, to new C in Nest."
But I'm looking at my old thermostat and the instructions said if you have a Rc and Rh thats coupled = dual transformer and not compatible for Nest E. That plus I don't have a wire for W1 (or maybe its broken off??) instead just a wire in W2. Which subsequent instructions stated that W2/O/B should go into the *O/B slot on the Nest. But I doubt that means to put both W2 and O wires into the *O/B slot on the Nest…
Really need some guidance on a dummies explanation for what to do. I was half tempted to just move forward and put wires in best I could, but physics101 warned me not to mess with electricity and improper connections. Some more context, just moved into the apartment. I believe its central Heating and AC. 
**Old thermostat
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