Task: Question Answering
Input (English): Problem: tom drives from town r to town b , driving at a constant speed of 60 miles per hour . from town b tom immediately continues to town c . the distance between r and b is twice the distance between b and c . if the average speed of the whole journey was 36 mph , then what is tom ' s speed driving from b to c in miles per hour ? 
Options: a ) 12 , b ) 20 , c ) 24 , d ) 30 , e ) 36
Output (English): b