You decide to purchase $100$ shares of QRS common stock at $$50$ per share, financing most of the purchase with your own funds and borrowing the rest of the necessary funds. If your initial margin is $60\%$ and your broker has set a maintenance margin at $55\%,$ what is your rate of return on the margin position if the stock price falls to $$48$ and you paid $$100$ in interest to your broker $($assume no dividends are paid$)?$