If electrode potential of following cell:
`Pt_(s)|Fe_(aq)^(2+),Fe_(aq)^(3+)||MnO_(4(aq))^(-),Mn_(aq)^(2+),H_(aq)^(+)|Pt_(s)`
is X then calculate value of 20X.
[Given: `E_(MnO_(4)^(-)|Mn^(2+)` = 1.51 V,`
`E_(Fe^(3+)|Fe^(2+))^(@)` = 0.78 V, (2.303 RT)/F = 0.06]`