尽可能化简．
口算。3-= -= 6÷= (+)×21313×89= 0.9×99+0.9= 1-+=2.3+ 3.57= 0.5×(2.6-2.4)= 0.25×4÷0.25×4=
42:=x:
x-x=
(2.5-2.5× 0.6)÷0.4
o.5÷[一（一]]
．
= 
-
= 6÷
= (
+
)×21
+
=
=x:
x=
一（
一
]] 
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