原式=9/10÷(1/2×(8/10-3/10)) =9/10÷(1/2×1/2) =9/10÷1/4=9/10*4 =18/5
9/10÷(1/2×(4/5-3/10)) =9/10÷1/2÷(8/10-3/10)=9/10×2×2=18/5
按运算顺序算就好啊 18/5
