Cell Potential#!#Trick To Learn Reduction Potential Values

Consider the following relations for (i) EMF of the cell =(Oxidation potential of anode) -(Reduction potential of cathode) (iii) EMF of the cell=(Reduction potential of anode) + (Reduction potential of cathode) (iv) EMF of the cell=(Oxidation potential of the anode)-(Oxidation potential of the cathode) which of the following above reactions are correct?

Standard reduction potential is calculated at

Consider the following relations for emf of a electrochemical cell (i) emf of cell = (Oxidation potential of anode)-(Reduction potential of cathode) (ii) emf of cell = (Oxidation potential of anode)+(Reduction potential of cathode) (iii) emf of cell = (Reduction potential of anode)+(Reduction potential of cathode) (iv) emf of cell = (Oxidation potential of anode)-(Oxidation potential of cathode) Which of the above realtions are correct?

Cathodic standard reduction potential minus anodic standard reduction potential is equl to