Task: Question Answering
Input (English): Problem: car x began traveling at an average speed of 35 miles per hour . after 72 minutes , car y began traveling at an average speed of 70 miles per hour . when both cars had traveled the same distance , both cars stopped . how many miles did car x travel from the time car y began traveling until both cars stopped ? 
Options: a ) 15 , b ) 20 , c ) 40 , d ) 42 , e ) 68
Output (English): d