数学题(英文)

nelston

there r 2 groups of worker.. skilled n partially skilled. if both group work togather they nid 30 days to finish the job. if partially skilled worker can oni do 2/3 of the skilled worker did in a day. how many days needed if only partially skilled worker is workin to finish the job?TVBNOW 含有熱門話題，最新最快電視，軟體，遊戲，電影，動漫及日常生活及興趣交流等資訊。; L7 b- p$ y& e4 \
A.50公仔箱論壇7 }" L  V6 x% ~5 ~" o' V! X0 T% }6 \
B.60TVBNOW 含有熱門話題，最新最快電視，軟體，遊戲，電影，動漫及日常生活及興趣交流等資訊。8 m( n! |) I4 R  x1 B
C.65TVBNOW 含有熱門話題，最新最快電視，軟體，遊戲，電影，動漫及日常生活及興趣交流等資訊。% x8 _% Z; P) n. m
D.75