1/8-5/7+6.875-2/7=1/8+6.875-(5/7+2/7)=1/8十6.875-1=0.125+6.875-1=7-1=6
1/8-5/7+6.875-2/7=(0.125+6.875)-(5/7+2/7)=7-1=6
1/8-5/7+6.875-2/7=(1/8+6.875)-(5/7+2/7)=(0.125+6.875)-(5+2)/7=7-1=6