If 50% of (x-y) = 30% of (x+y) then what percent of x is y?
Choose the correct option:
A) 2.5 %  B) 10 %  C) 5 %  D) 15 %  E) 25 %

Rationale: "50 % of ( x - y ) = 30 % of ( x + y ) ( 50 / 100 ) ( x - y ) = ( 30 / 100 ) ( x + y ) 5 ( x - y ) = 3 ( x + y ) 2 x = 8 y x = 4 y therefore required percentage = ( ( y / x ) x 100 ) % = ( ( y / 4 y ) x 100 ) = 25 % answer is e ."
Answer: E