If 50% of (x-y) = 20% of (x+y), then what percent of x is y?  Choose the correct choice from the following options
A) 50.5 % B) 42.8 % C) 22.2 % D) 33.3 % E) 25 %

Rationale: "50 % of ( x - y ) = 20 % of ( x + y ) 50 / 100 ( x - y ) = 20 / 100 ( x + y ) 3 x = 7 y required percentage = y / x * 100 = 3 y / 7 y * 100 = 42.85 % answer is b"
Answer: B