BEIJING—China said it would slash tariffs on $75 billion of U.S. imports in half as part of its efforts to implement a recently signed trade agreement with Washington. Beginning Feb. 14, China will cut tariffs on some U.S. goods to 5% from 10%, while levies on some other items will be reduced to 2.5% from 5%, China’s Ministry of Finance said in a statement Thursday. The tariffs were imposed in September and December during a brutal trade fight between the world’s two largest economies. …