Elisa needs money to repair her home air conditioner, so she pawns her bicycle. The pawnbroker loans Elisa $270. Twelve days later, Elisa gets her bicycle back by paying the pawnbroker $291.60. What annual simple interest rate did the pawnbroker charge Elisa? Assume 360 days in a year. The pawnbroker charged Elisa a simple interest rate of (Round to the nearest whole number as needed.) %