if 50% of (x-y) = 40% of (x+y) then what percent of x is y?	Choose the correct choice from the following:
A) 2.5 % B) 11 % C) 5 % D) 15 % E) 25 %

Rationale: "50 % of ( x - y ) = 40 % of ( x + y ) ( 50 / 100 ) ( x - y ) = ( 40 / 100 ) ( x + y ) 5 ( x - y ) = 4 ( x + y ) x = 9 y x = 9 y therefore required percentage = ( ( y / x ) x 100 ) % = ( ( y / 9 y ) x 100 ) = 11 % answer is b ."
Answer: B