Task: Question Answering
Input (English): Problem: running at their respective constant rate , machine x takes 2 days longer to produce w widgets than machines y . at these rates , if the two machines together produce 5 w / 4 widgets in 3 days , how many days would it take machine x alone to produce 3 w widgets . 
Options: a ) 4 , b ) 6 , c ) 18 , d ) 10 , e ) 12
Output (English): c