问题描述：
一道英语奥数题
there is a road to be repaired.A needs 10days to finish,B needs 12days and C needs 15days .Now they work together to mend the road.A left halfway,in the end ,they spent 6days finishing the road.After A left,find out how many days did B and C work together?
there is a road to be repaired.A needs 10days to finish,B needs 12days and C needs 15days .Now they work together to mend the road.A left halfway,in the end ,they spent 6days finishing the road.After A left,find out how many days did B and C work together?
问题解答：
我来补答展开全文阅读