A year ago, Kim Altman purchased $160$ shares of BLK$,$ Inc. for $$35\mathrm{.}50$ on margin. At that time the margin requirement was $20$ percent. If the interest rate on borrowed funds was $6$ percent and she sold the stock for $$40\mathrm{.}50,$ what is the percentage return on the funds she invested in the stock? Round your answer to two decimal places.