设乙队休息了X天,则合作时间为16-3-X=13-X天
(1/20+1/30)×(13-X)+3/30+X/20=1
(13-X)/12+1/10+X/20=1
10×(13-X)/120+12/120+6X/120=1
130-10X+12+6X=120
142-4X=120
4X=22
X=5.5
答:乙队休息了5.5天.
设乙队休息了X天,则合作时间为16-3-X=13-X天
(1/20+1/30)×(13-X)+3/30+X/20=1
(13-X)/12+1/10+X/20=1
10×(13-X)/120+12/120+6X/120=1
130-10X+12+6X=120
142-4X=120
4X=22
X=5.5
答:乙队休息了5.5天.