DETROIT - General Motors Co reported record quarterly earnings before charges for the third quarter, as strong demand for trucks in North America and improved profit margins in China overcame declining revenues. GM said it earned $1.50 a share in the quarter ended Sept. 30, up 55 percent from a year ago and well ahead of the $1.18 per share consensus among Wall Street analysts polled by Thomson Reuters I/B/E/S. Including $1.5 billion in costs for expenses related to the settlement of a U.S. Justice Department investigation of the automaker’s mishandled ignition switch recall, GM said net income for the latest quarter was 84 cents a share, up from 81 cents a share.