The Bill and Melinda Gates Foundation is giving a $10 million low-cost loan to help increase the number of seats available in charter schools in and around the distressed community of Central Falls. On Tuesday, the foundation announced the funding, which will be used to provide low- and no-interest loans for projects that increase the availability of seats available in high-performing schools to students from Central Falls. Officials said they could ultimately leverage the money for $50 million in building projects. Five to seven schools could be helped.