Consider the relation,$2Ag^++Cd\rightarrow 2Ag+Cd^{+2}$ the standard electrode potentials for $Ag^+/Ag$ and $Cd^{+2}/Cd$ couples 0.8V and 0.04V respectively.What is the standard potential for this reaction?

Question

$\begin{array}{1 1}(a)\;0.2V&(b)\;0.4V\\(c)\;0.5V&(d)\;0.3V\end{array}$