LG Electronics Inc. on Tuesday estimated its third-quarter operating earnings at 751.1 billion won (US$556.9 million), down 20.9 percent from a year earlier.Sales increased 10.7 percent to 22.17 trillion won. The data for net earnings was not available.The operating profit was 22.5 percent lower than the average estimate, according to a survey by Yonhap Infomax, the financial data firm of Yonhap News Agency.The company will release its final earnings report later.Source: Yonhap News Agency