请用普通的递等式算法计算，不然我会看不懂的……
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
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
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……
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
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