(3/7+3/8+5/9+7/10)/(3/8+7/10+3/7)=(3/8+7/10+3/7)/(3/8+7/10+3/7)+(5/9)/(3/8+7/10+3/7)=1+(5/9)/(3/8+7/10+3/7)=1+1400/3789 嘛 这算什么啊....
