The annual interest rate earned by an investment increased by 10 percent from last year to this year. If the annual interest rate earned by the investment this year was 13 percent, what was the annual interest rate last year? Choose the correct answer.
A) 1 %	B) 1.1 %	C) 9.1 %	D) 11.81 %	E) 11.50 %

Rationale: 13 = 1.1 * x x = 11.81 % answer d )
Answer: D