口算。 380+250= 100﹣64= 15×5= 72÷3= 4.8+5.2= 10﹣0.4= 1.7×0.4= 8.4÷21= += ﹣= ×= ÷=
325×0.36+6.75×36
5.6×0.375+×5.4-0.375×0.9
5.6x+4x=17.28
x+=
[一（一）]÷
+
= 
﹣
= 
×
= 
÷
=
×5.4-0.375×0.9
x+
=
一（
一
）]÷
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