20/13÷7+1/7*6/13 =20/91+6/91=26/91=2/72/3+7/6*2/3÷6/7=2/3+7/6*2/3*7/6=2/3(1+49/36)=2/3*85/36=170/108=85/54x-75%=5/8 x=5/8+3/4=11/814÷(3/4-1/7)=14*28/17=392/17(8/9-5/12+=1/4)*36