21.36÷0.8-12.9的简算

请用普通的递等式算法计算，不然我会看不懂的……

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21.36÷0.8-12.9

=21.36÷4／5-12.9
=21.36×5／4-12.9
=5·34×5-12.9
=26·7－搏樱启基如颂让12.9
=13·8

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21.36÷0.8-12.9

=21.36÷4／颂让5-12.9
=21.36×5／搏樱启4-12.9=21.36÷4×5-12.9
=5·34×5-12.9
=26·7－基如12.9
=13·8

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