23/5X9/10+27/5-10/9如果要简便运算的话,这个减应该改变除以,否则如下运算 =207/50+270/50-10/9 =477/50-10/9=4293/450-500/450=3793/450 改为除以后,运算如下 =23/5X9/10+27/5X9/10 =(23/5+27/5)X9/10 =10X9/10 =9 (8/9-1/3)/(7/18X2/3) =(8/9-3/9)/(7/27) =5/9X27/7 =15/7