28.8÷[(1.28-0.56)×8]=28.8÷[0.72×8]=28.8÷5.76=5
28.8÷[(1.28-0.56)×8]=5 商是5
(1.28-0.56)×8÷28.8=0.72×8÷28.8=5.76÷28.8=0.2
(1.28-0.56)x8÷28.8=0.2