设从甲地开往乙地时上坡路x,下坡路y,则x/56 + y/80 =3.75从乙地开往甲地时,上坡路下坡路与原来刚好相反,所以x/80 + y/56 =3.9解方程组 x/56 + y/80 =3.75 x/80 + y/56 =3.9解得x=112,y=140甲、乙两地之间...