设原定车速为x km/h,原定时间为y h
x(1+20%)*(y-0.5)=xy
1.2xy-1.2x*0.5=xy
0.2xy=0.6x
y=3
x(1-20%)*(y+0.5)=xy-45
0.8xy+0.8x*0.5=xy-45
0.4x=0.2xy-45
4x=2x*3-450
2x=450
x=225
甲乙两地相距:xy=225*3=675km
设原定车速为x km/h,原定时间为y h
x(1+20%)*(y-0.5)=xy
1.2xy-1.2x*0.5=xy
0.2xy=0.6x
y=3
x(1-20%)*(y+0.5)=xy-45
0.8xy+0.8x*0.5=xy-45
0.4x=0.2xy-45
4x=2x*3-450
2x=450
x=225
甲乙两地相距:xy=225*3=675km