The task is to generate the correct answer for a given math problem.

[EX Q]: Problem: how many multiples of 7 are there between 10 and 100 ( both are inclusive ) ?
[EX A]: 13

[EX Q]: Problem: 5 years ago , paula was 3 times as old as karl . in 6 years , paula will be twice as old as karl . what is the sum of their ages now ?
[EX A]: 54

[EX Q]: Problem: a train travels from new york to chicago , a distance of approximately 540 miles , at an average rate of 60 miles per hour and arrives in chicago at 6 : 00 in evening , chicago time . at what hour in the morning , new york time , did the train depart for chicago ? ( note : chicago time is one hour earlier than new york time )
[EX A]:
10 : 0