Katie puts up $5,000 but borrows an equal amount of money from her broker to double the amount invested to $10,000. The broker charges 8% on the loan. The stock was originally purchased at $50 per share, and in 1 year Katie sells the stock for $55. What was Katie's rate of return? Type your answer as a percentage, not as a decimal. (Answer 10%, 15%, 20%, etc.)