Consider the following equations : 2 Fe ^ 2 + + H _ 2 O _ 2 → xA +...

Consider the following equations :
$2{Fe}^{2 +} + {H}_{2}{O}_{2} \to xA + yB$

(in basic medium)

$2{MnO}_{4}^{-} + 6{H}^{+} + 5{H}_{2}{O}_{2} \to {x}^{'}C + {y}^{'}D + {z}^{'}E$

(in acidic medium)

The sum of the stoichiometric coefficients $x, y, {x}^{'}, {y}^{'}$ and ${z}^{'}$ for products $A, B, C, D$ and $E$ respectively, is _______