Task: Question Answering
Input (English): Problem: john purchased some shirts and trousers for $ 700 . he paid $ 400 less for the shirts than he did for the trousers . if he bought 5 shirts and the cost of a shirt is $ 20 less than that of a trouser , how many trousers did he buy ? 
Options: a ) 4 , b ) 5 , c ) 6 , d ) 7 , e ) 11
Output (English): e