减一除→乘:a ÷ b – c × d
除→减→乘:a ÷ b – c × d
减→乘→除:a ÷ b – c × d
7.25+2.75= 0.638×1000= 530÷100= 23×0÷100=
20-20÷5= 6.66-3.36= 36+0÷11= 25×12×4=
①125×32×25
②30.6+3.55+6.45+9.4
③25×(400+40)
④(35+35+35+35)×25