把下列分数化成最简分数= = == = =
用竖式计算下面各题 800﹣260= 680+270= 74﹣16= 25+36=
□○□○□=□ ．
比一比，算一算．
列竖式计算下面各题． 99﹣14= 20+16= 75+7= 72﹣27=
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