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0.75x63.9+6.39+2.5用简算

题目详情
0.75x63.9+6.39+2.5用简算
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答案和解析
0.75x63.9+6.39+2.5
=7.5x6.39+6.39+2.5
=(7.5+2.5)x6.39
=10×6.39
=63.9