Solution manual says that the total surface charge density of (b) is +σ in upper plate. so it equals to E and ε_0V/d. But it seems wrong. +σ is not talal charge density but free charge density. isn’t it? I mean
σ_total=σ_free+σ_bound=σ + σ_bound
I wonder if I thought wrong. It would be appreciated when someone help me.
ps: I attached the problem and solution
I didn’t write in the form that PF gives, because my question is very simple.