DETROIT (AP) — With its sales slowing and its stock price tumbling, Tesla Inc. slashed prices dramatically Friday on several versions of its electric vehicles, making some of its models eligible for a new federal tax credit that could help spur buyer interest. The company dropped prices nearly 20% in the United States on some versions of the Model Y SUV, its top seller. That cut will make more versions of the Model Y eligible for a $7,500 electric-vehicle tax credit that will be available through March.