Plz solve this question plea for the reaction

Dear student In the reaction : MnO2 --> Mn2+ + MnO4- can be splitted into two reactions. Equivalent mass of MnO2 is calculated in both cases: i) MnO2 --> Mn2+ Here 2 electrons are involved in reduction,so equivalent mass = molar mass /2 = M/2 ii) MnO2 --> MnO4- Here oxidation state changes from (+4 to +7, so three electrons are involved in the reaction. Equivalent weight = molar mass/3 =M/3. Equivalent weight of the species undergoing disproportionation =Eq. wt. (in oxidation) + Eq. wt. (in reduction), so, M/2 + M/3 = 5M/6. (option4) Regards