Task: Question Answering
Input (English): Problem: if two trains are 120 miles apart and are traveling toward each other at constant rate of 30 miles per hour and 40 miles per hour , respectively , how far apart will they be 1 hour before they meet ? 
Options: a ) 10 , b ) 30 , c ) 40 , d ) 50 , e ) 70
Output (English): e