84. Grounds for which candidate other than the returned candidate may be declared to be elected.

(a) in fact the petitioner or such other candidate received a majority of the valid votes; or
(b) that but for the votes obtained by the returned candidate by corrupt practices the petitioner or such other candidate would have obtained a majority, of the valid votes, the Tribunal shall after declaring the election of the returned candidate to be void, declare the petitioner or such other candidate, as the case may be, to have been duly elected.
(a) any decision made by the Returning Officer under clause (b) of rule 63 shall, in so far as it determines the question between those candidates, be effective also for the purpose of the petition; and
(b) in so far as that question is not determined by such a decision, the Tribunal shall decide between them by lot and proceed as if the one on whom the lot then falls has received an additional vote.