In an electrochemical reaction of lead, at standard temperature, if E_( Pb^2+ / Pb )^°= m Volt and E_( Pb^4+ / Pb )^°= n Volt, then the value of E_(…

In an electrochemical reaction of lead, at standard temperature, if $\displaystyle \mathrm{E}_{\left(\mathrm{Pb}^{2+} / \mathrm{Pb}\right)}^{\circ}=\mathrm{m}$ Volt and $\displaystyle \mathrm{E}_{\left(\mathrm{Pb}^{4+} / \mathrm{Pb}\right)}^{\circ}=\mathrm{n}$ Volt, then the value of $\displaystyle \mathrm{E}_{\left(\mathrm{Pb}^{2+} / \mathrm{Pb}^{4+}\right)}^{\circ}$ is given by $\displaystyle \mathrm{m}-\mathrm{xn}$. The value of x is $\displaystyle \_\_\_\_$.(Nearest integer)