Flipping the Anode

[MorganYun1H]

I am confused when you would flip the oxidation half reaction? Also, there were some problems in the homework where you're calculating Ecell from the E of both half reactions, and they don't flip the sign? So how do you know when to flip the sign of E?

[Riya Pathare 2E]

When you are using E(naut)=E(cathode)-E(anode) they are talking about the reduction potentials so we don't flip anything. But when we are adding the half reactions we flip the most negative half reaction so we get a positive cell potential with the entire balanced equation.