原式=6/7﹢3/4﹢2/7﹣4/11﹣3/4﹣7/11 =8/7﹢3/4﹣3/4﹣4/11﹣7/11 =1/7
(6/7+3/4)+(2/7-4/11)-(3/4+7/11)=6/7+3/4+2/7-4/11-3/4-7/11=(6/7+2/7)+(3/4-3/4)-(4/11+7/11)=8/7+0-1=1/7