一項(xiàng)工程,甲、乙兩隊(duì)合做30天完成,現(xiàn)在甲隊(duì)單獨(dú)做24天后,乙隊(duì)加入,兩隊(duì)又合做了12天,這時(shí)甲隊(duì)調(diào)走,乙隊(duì)繼續(xù)做15天才完成這項(xiàng)工程.甲隊(duì)單獨(dú)做這項(xiàng)工程需多少天?
1÷[(1-
)÷(24-15)]
=1÷[(1-
)÷9],
=1÷[
÷9],
=1
÷,
=90(天).
答:甲隊(duì)單獨(dú)做這項(xiàng)工程需90天.