方法一、返回时用了 t 小时,55(10 - t) = 45t11(10 - t) = 9t20t = 110t = 5.5 小时方法二、甲乙两港间的路程为 s 千米.s/55 + s/45 = 10两边同乘以 495 得9s + 11s = 495020s = 4950s = 247.5 千米返回时用了 t 小...