San Francisco voters backed a tax on the city’s wealthiest companies to tackle homelessness, passing a measure that divided the tech community. A tally posted Wednesday showed that 60 percent of voters in the city home to Airbnb, Uber, Salesforce, and Twitter cast ballots in favor of “Proposition C,” a local ballot measure brought about by a 28,000 signature petition this summer. A number of San Francisco’s tech bosses — including Twitter chief Jack Dorsey and Patrick Collison of payment startup Stripe — resisted the proposal.