Working simultaneously at their respective constant rates, Machines and
produce 20 widgets in
hours. Working alone at its constant rate, Machine
produces 20 widgets in
hours. In terms of
and
, how many hours does it take Machine
, working alone at its constant rate, to produce 10 widgets?
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数学PS
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-
A
-
B
-
C
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D
-
E
显示答案
正确答案: D