（2/17+2/21）×17×21
=2/17×17×21+2/21×21×17
=42+34
=76
=2/17×17×21+2/21×21×17
=42+34
=76
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第1个回答 2017-02-21
（17分之1+21分之2）×17×21
=（1/17+2/21）×17×21
=(1/17)x17×21 + (2/21)×17×21
=21 + 2x17
=21 +34
=55
=（1/17+2/21）×17×21
=(1/17)x17×21 + (2/21)×17×21
=21 + 2x17
=21 +34
=55
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