13) In an association, each member has the right to vote for the president. The current president was elected with a number of votes double those obtained by his only opponent. Knowing that three members did not vote and that the elected president received $64\%$ of the votes of those entitled to vote, determine the total number of members.
(A) 69,
(B) 75
(C) 81,
(D) 87
(E) 99.
13. The answer is $\mathbf{( B )}$.

The defeated candidate received $32 \%$ of the votes, which, when added to the $64 \%$ of the votes for the elected candidate, give $96 \%$ of the votes of the eligible voters. The 3 members who did not vote therefore correspond to the $4 \%$ of the eligible voters. If we denote the total number of members by $x$, then $3: x=4: 100$ from which we obtain $x=75$.