project will be done by Team A alone for 12 days, and then Team B will take over. After Team B worked alone for 20 days, Team A came back to cooperate with Team B again. When the two teams cooperated, the work efficiency of team A increased (1/5) compared to the original, and the work efficiency of team B doubled. After 15 days of cooperation, the whole project was exactly half completed. Then, how many days after the two teams cooperate, they can finish the rest of the work.
一项工程先由甲队独做12天，再由乙队接手．乙队独做20天后，甲队又回来与乙队合作．在两队合作时，甲队工作效率比原来提高了(1/5)，乙队的工作效率则提高了1倍，这样合作15天后，整个工程恰好完成了一半．那么，甲、乙两队再合作多少天就可以把剩下的工作做完．
<result>25</result>