Janet likes to gamble, and she is so successful she keeps an account with her local bookie. She starts on January 1 with $11,000. On March 1, she deposits another $4,000. On September 1 she withdraws $X and on November 1 she again deposits $4,000. At the end of the year, her account is worth $15,000 and the dollar weighted return on her investment is 7.5%. Find X.