hello , i am looking for a train out of cambridge .
user
what day would you be traveling and where would you like to go ?
assistant
i would be leaving on friday and i would be traveling to london liverpool street and i would like to leave after 21:15
user
you could take the tr9557 at 21:59 , or the tr3138 2 hour -s later .
assistant
i'll take the earlier train . could you tell me the travel time , and at what time i will be arriving at london liverpool street ?