设乙X km/h,水速Y km/h
(1)没有相遇 2(x+y)+2(39+y)=10【(39+y)-(x+y)】+60
x=31
(2)相遇又相距60km 2(x+y)+2(39+y)=10【(39+y)-(x+y)】-60
x=21
乙船速度31km/h或21km/h
设乙X km/h,水速Y km/h
(1)没有相遇 2(x+y)+2(39+y)=10【(39+y)-(x+y)】+60
x=31
(2)相遇又相距60km 2(x+y)+2(39+y)=10【(39+y)-(x+y)】-60
x=21
乙船速度31km/h或21km/h