x+1/2=6/7 x=6/7-1/2 x=12/14-7/14 x=5/143/8-x=7/20 x=3/8-7/20 x=15/40-14/40 x=1/40
1、x+1/2=6/7x=6/7-1/2x=12/14-7/14x=5/122、3/8-x=7/20x=3/8-7/20x=15/40-17/40x=-2/40=1/20
