Task: Question Answering
Input (English): Problem: one hour after yolanda started walking from x to y , a distance of 52 miles , bob started walking along the same road from y to x . if yolanda ' s walking rate was 3 miles per hour and bob т ' s was 4 miles per hour , how many miles had bob walked when they met ? 
Options: a ) 28 , b ) 23 , c ) 22 , d ) 21 , e ) 19.5
Output (English): a