解:3/10÷9+1/9×7/10=1/9(3/10+7/10)=1/97/8×5/3+7/8÷3=7/8(5/3+1/3)=7/8x2=7/44/5×6÷4/5×6=(4/5x6)/(4/5x6)=1;3不明白可以追问,有用请采纳!