Legislation that would have allowed all cities in California to use ranked-choice voting, the system in San Francisco and three other Bay Area communities that lets voters rank candidates by preference and decide an election in a single round of ballots, has been vetoed by Gov. Jerry Brown. Ranked-choice, also known as instant-runoff voting, gives voters the option of choosing multiple candidates in order of preference. After the ballots are first counted, the candidate with the fewest top-rank votes is eliminated and the next choices of that candidate’s supporters are apportioned among the remaining candidates. The process continues until one candidate gets a majority.