两队修一条公路,甲队每天修全长的1/5,乙队独做7.5天修好.如果两队合修2天后,其余由乙队独修,还要几天完成?

问题描述:

两队修一条公路,甲队每天修全长的1/5,乙队独做7.5天修好.如果两队合修2天后,其余由乙队独修,还要几天完成?

[1-(

1
5
+
1
7.5
)×2]÷
1
7.5

=[1-
1
3
×2]÷
1
7.5

=[1-
2
3
]÷
1
7.5

=
1
3
÷
1
7.5

=2.5(天),
答:还要2.5天完成.