Task: Question Answering
Input (English): Problem: a driver would have reduced the time it took to drive from home to the store by 1 / 4 if the average speed had been increased by 10 miles per hour . what was the actual average speed , in miles per hour , when the driver drove from home to the store ? 
Options: a ) 12 , b ) 15 , c ) 20 , d ) 25 , e ) 30
Output (English): e