Task: Question Answering
Input (English): Problem: a retailer bought a machine at a wholesale price of $ 90 and later on sold it after a 10 % discount of the retail price . if the retailer made a profit equivalent to 20 % of the whole price , what is the retail price r of the machine ? 
Options: a ) 81 , b ) 100 , c ) 120 , d ) 135 , e ) 160
Output (English): c