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> Thereisapieceofwork.IttakesMr.Aalone20daystofinish,andMr.B30alonedaystofinish.Ittakesthem()daystowor
Thereisapieceofwork.IttakesMr.Aalone20daystofinish,andMr.B30alonedaystofinish.Ittakesthem()daystowor
题目简介
Thereisapieceofwork.IttakesMr.Aalone20daystofinish,andMr.B30alonedaystofinish.Ittakesthem()daystowor
题目详情
There is a piece of work.It takes Mr.A alone 20 days to finish,and Mr.B 30 alone days to finish.It takes them( )days to work together to finish the work.
A.10
B.12
C.15
D.50
题目简介
Thereisapieceofwork.IttakesMr.Aalone20daystofinish,andMr.B30alonedaystofinish.Ittakesthem()daystowor
题目详情