①(-)÷
②×+÷11
③5÷[(-)×]
×= ÷4= 1÷= ×0=
-= +1= 3.5×= ×40=
400÷80= 7.7+2.3= 4.2÷0.6= 1﹣0.91=
0.04×1000= 10÷1.25×9= 24×0.25= 23﹣1=
+= ×20=