575-78+58的简便计算。解：根据结合律的运用，原式=575-（78-58）=575-20=555
575-78+58=575-58+58 -20=575-20=555
575-78+58=575-75+58-3=500+58-3=558-3=555
575-78+58=575-(78-58)=575-20=555欢迎采纳
