Task: Question Answering
Input (English): Problem: if a certain toy store ' s revenue in november was 2 / 5 of its revenue in december and its revenue in january was 1 / 2 of its revenue in november , then the store ' s revenue in december was how many times the average ( arithmetic mean ) of its revenues in november and january ? 
Options: a ) 1 / 4 , b ) 1 / 2 , c ) 10 / 3 , d ) 2 , e ) 4
Output (English): c