Task: Question Answering
Input (English): Problem: noelle walks from point a to point b at an average speed of 3 kilometers per hour . at what speed , in kilometers per hour , must noelle walk from point b to point a so that her average speed for the entire trip is 5 kilometers per hour ? 
Options: a ) 15 , b ) 12.5 , c ) 10 , d ) 8 , e ) 7.75
Output (English): a