甲为 1
乙/甲=乙/1=3/4
乙=3/4
丙/乙=丙/ 3/4=3/5
丙=9/20
和 1+3/4+9/20 = 11/5
甲 1/ 11/5 = 5/11
乙 3/4 / 11/5 = 15/44
丙 9/20 / 11/5 = 45/220
甲为 1
乙/甲=乙/1=3/4
乙=3/4
丙/乙=丙/ 3/4=3/5
丙=9/20
和 1+3/4+9/20 = 11/5
甲 1/ 11/5 = 5/11
乙 3/4 / 11/5 = 15/44
丙 9/20 / 11/5 = 45/220