1+1/3-7/12+9/20-11/30+13/42-15/56 =1+1/3-(1/3+1/4)+(1/4+1/5)-(1/5+1/6)+(1/6+1/7)-(1/7+1/8) =1+1/3-1/3-1/4+1/4+1/5-1/5-1/6+1/6+1/7-1/7-1/8 =1-1/8 =7/8 以上回答你满意么?
