Task: Question Answering
Input (English): Problem: in a coconut grove , ( x + 4 ) trees yield 60 nuts per year , x trees yield 120 nuts per year and ( x – 4 ) trees yield 180 nuts per year . if the average yield per year per tree be 100 , find x . 
Options: a ) 3 , b ) 4 , c ) 8 , d ) 9 , e ) none of the above
Output (English): c