4620+(401-438÷73) =4260+(401-6), =4260+395, =4655; 520×(80-720÷9) =520×(80-80), =520×0, =0; 350-(350-350÷70), =350-(350-50), =350-300, =50; 5580-(120×25-2991), =5580-(3000-2991), =5580-9, =5571; (300-1456÷26)×32, =(300-56)×32, =244×32, =7808; 642-(36+132)÷4, =642-168÷4, =642-42, =600. |