请教OG11-79-快考试了！急救！

sophia417

While on a straight road, car X and car Y are traveling at different constant rates. If car X is now 1 mile ahead of car Y, how many minutes from now will car X be 2 miles ahead of car Y?

i) Car X is traveling at 50 miles per hour and car Y is traveling at 40 miles per hour.

ii) Three minutes ago car X was 1/2 mile ahead of car Y.

答案选择C。

我实在是想不明白，也不大明白OG的解释。

请教啊！！><

[此贴子已经被作者于2009-3-11 12:07:20编辑过]

sophia417

自己顶一个