3.6+6.02+1.98=3.6+（6.02+1.98）这里是运用加法 律．
：20=3： =0.2== %
=== ÷12．
18÷ == ÷5= ．
=0.625==15÷ ．
1÷8== （填小数）= %
= %
=
=
= ÷12．
= ÷5= ．
=0.625=
=15÷ ．
= （填小数）= %
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