设甲速为xkm/h,乙速为ykm/h,则:
x+y=30……(1)
(20/60+5又40/60)x+30=5又40/60*y……(2)
由(2)得:6x+30=17y/3
18x-17y=-90………………(4)
(1)*17+(4)得:35x=420
x=12
将x=12代入(1)得:y=18
即甲速为12km/h,乙速18km/h .
设甲速为xkm/h,乙速为ykm/h,则:
x+y=30……(1)
(20/60+5又40/60)x+30=5又40/60*y……(2)
由(2)得:6x+30=17y/3
18x-17y=-90………………(4)
(1)*17+(4)得:35x=420
x=12
将x=12代入(1)得:y=18
即甲速为12km/h,乙速18km/h .