Task: Question Answering
Input (English): Problem: fred and sam are standing 40 miles apart and they start walking in a straight line toward each other at the same time . if fred walks at a constant speed of 4 miles per hour and sam walks at a constant speed of 4 miles per hour , how many miles has sam walked when they meet ? 
Options: a ) 5 , b ) 9 , c ) 20 , d ) 30 , e ) 45
Output (English): c