2/9+3/8+5/8-1/9=(3/8+5/8)+(2/9-1/9)=1+1/9=1又1/9 1/4+1/3+(2/3-1/4)=(1/4-1/4)+(1/3+2/3)=0+1=1
图望采纳……………
答案见图……