Task: Question Answering
Input (English): Problem: the length of a rectangle is twice its breadth . if its length is decreased by 5 cm and breadth is increased by 5 cm , the area of the rectangle is increased by 75 sq . cm . find the length of the rectangle . 
Options: a ) 5 , b ) 10 , c ) 15 , d ) 20 , e ) none of them
Output (English): d