Task: Question Answering
Input (English): Problem: 6 computers , each working at the same constant rate , together can process a certain amount of data in 9 days . how many additional computers , each working at the same constant rate , will be needed to process the same amount of data in 6 days ? 
Options: a ) 3 , b ) 5 , c ) 6 , d ) 9 , e ) 12
Output (English): a