Task: Question Answering
Input (English): Problem: car a travels at 3 times the average speed of car b . car a started to travel at 12 : 00 o ' clock , car b started to travel at 16 : 00 o ' clock . what is the speed of car b ( in km / h ) if the total distance that both cars traveled until 18 : 00 was 1000 km ? 
Options: a ) 10 . , b ) 25 . , c ) 30 . , d ) 38 , e ) 50 .
Output (English): e