Task: Question Answering
Input (English): Problem: a bus trip of 450 miles would have taken 1 hour less if the average speed s for the trip had been greater by 5 miles per hour . what was the average speed s , in miles per hour , for the trip ? 
Options: a ) 10 , b ) 40 , c ) 45 , d ) 50 , e ) 55
Output (English): c