1、8÷38×5.7+2.5÷3 2、39×（31 - 知识问答

1、8÷38×5.7+2.5÷3 2、39×（31/56+7/22）+17×（31/56-7/22）（写出过程）

2个回答

8÷38×5.7+2.5÷3
＝4/19x5.7+5/2x1/3
=1.2+5/6
=6/5+5/6
=36/30+25/30
=61/30
39×（31/56+7/22）+17×（31/56-7/22）
=39x31/56+39x7/22+17x31/56-17x7/22
=(39+17)x31/56+(39-17)x7/22
=56x31/56+22x7/22
=31+22
=53

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