Robert's salary was decreased by 30% and subsequently increased by 30%. how much percentage does he lose?  Choose the most appropriate option: A) 10 % B) 9 % C) 25 % D) 30 % E) 50 %

Rationale: "let original salary be $ 100 salary after decreasing 30 % = 100 - 100 x 30 / 100 = $ 70 salary after increasing 30 % on $ 70 = 70 + 70 x 30 / 100 = $ 91 percentage of loss = 100 - 91 = 9 % answer : b"
Answer: B