Task: Question Answering
Input (English): Problem: at a certain fruit stand , the price of each apple is 40 cents and the price of each orange is 60 cents . mary selects a total of 20 apples and oranges from the fruit stand , and the average ( arithmetic mean ) price of the 20 pieces of fruit is 56 cents . how many oranges must mary put back so that the average price of the pieces of fruit that she keeps is 52 cents ? 
Options: a ) 6 , b ) 7 , c ) 8 , d ) 9 , e ) 10
Output (English): e