Task: Question Answering
Input (English): Problem: a bus trip of 660 miles would have taken 1 hour less if the average speed v for the trip had been greater by 5 miles per hour . what was the average speed v , in miles per hour , for the trip ? 
Options: a ) 40 , b ) 45 , c ) 50 , d ) 55 , e ) 60
Output (English): d