(c)After reservation of offices for the Scheduled Castes and the Scheduled Tribes, the number of offices to be reserved for the Backward Classes for the office of Mayor and Chairperson within the state as the case may be shall be such number within the overall limit of fifty percent reservation for the Scheduled Castes, the Scheduled Tribes and the Backward Classes in the manner prescribed; and such offices shall be allotted to the remaining municipalities by rotation by the State Election Commission in the manner prescribed by it;