57/58-17/48-48分之七减58分之一=57/58-1/58-（17/48+7/48）=56/58-24/48=28/29-1/2=56/58-29/58=27/58
57/58-17/48-7/48-1/58，等于57/58-1/58减括号17/48+7/48括号，等于28/29-1/2，等于56/58-29/58，等于27/58
等于0.465517241379
