①75.8÷4÷2.5
②43.5×99+43.5
③350÷4÷3.5
④25.6﹣22.78+3.4
①12.7﹣3.6﹣5.4
②
③
④
①-+-
②×+÷
③(6﹣1.3×4)÷0.1
④0.4×0.25×8×125
⑤3.4÷[(1.25+0.45)×23]