脱式计算.450+(682﹣309)= 904﹣327+156=
计算:= 1﹣= = = == = 1﹣= = =
+=﹣==改正:
用推算计算(1)+=(2)﹣=
计算:2.5×40= 18×6= 1.73+2.07= 10﹣0.9= 400÷4=+= ﹣= += ﹣= ﹣=
计算下面各题,能简算的要简算.﹣+ ﹣(﹣) 5﹣﹣ +(﹣)﹣(+) +++.