An investor puts up $5,000 but borrows an equal amount of money from his broker to double the amount invested to $10,000. The broker charges 7% on the loan. The stock was originally purchased at $25 per share, and in 1 year the investor sells the stock for $28. The investor's rate of return was (12 points) A) What is the investor's percentage margin in his/her margin account by end of year one? (4 points)