①100﹣600÷25×4
②20﹣ ﹣
③13× +5×
④[ ﹣( + )]÷
⑴3.14×52×8﹣3.14×42×7.5 ⑵(+)÷ ⑶4.6×[1÷(2.1﹣2.08)]
12﹣3.6= 12×0.5= 36×25%= ×6+=
+= ÷4= 0××5= 28÷1.25÷8=