设:乙车速度为Xkm/h,两地相距Ykm.
则:((Y/2)+28)/(X+10)=((Y/2)-28)/X
(Y/2)/(X+10)+3/4=(Y/2)/X
将上述方程联立求解
XY+56X=XY-56X+10Y-560
2XY+3X^2+30X=2XY+20Y
112X+560=10Y
3X^2-20Y+30X=0
3X^2-224X+30X-1120=0
3X^2-194X-1120=0
(X-70)(3X+16)=0
X1=70X2=-5.33舍去
X=10=80
Y=(112×70+560)/10=840
甲车时速80,乙车时速70,两地相距840km